Castle of Slimes

Unknown Canyon

(Y/N)'s POV

Another new day, another mission handed down by the archduke. Finally, some work to do after all the boring stuff these past few days! I was excited, but I was still left confused. More to the point as to why we were in some kind of canyon on a carriage going to our location. I was also confused by the current stated of Rias, Koneko and Asia, who all looked incredibly tired and exhausted. Akeno on the other hand looked chipper as usual. I wonder if it had anything to do with the mission. I bet they're still trying to recover from yesterday.

My curiosity got the better of me, so I scooted over to Akeno, who was sitting on my right and I leaned closer to her ear, hoping to ask some questions. "Hey, so why are we going to the mission location by carriage? As much as I hate to say it, couldn't we have just teleported there with a magic circle?" I shuttered at the thought of teleporting by magic circle again.

"Well sweetie, the thing is, our mission's location is protected by some form of barrier, and it seems to cover a majority of the area around it. Reports say that it's an ancient spell that had been recorded as impossible to break. Many have tried, but none had proven successful. So, as a resort, the only way to get to the location is by going through this canyon." She said with a smile.

"Okay, I get that. But why by carriage?" I asked.

"The terrain here is a little too unstable for any automotive vehicles, so carriage is the best way. Plus, it's way better than walking."

"I guess." I said with a sigh. "Now, on to you three." I added, mentioning the three girls who looked fairly unhappy. "What's the deal? Why do you three look so glum?" I asked. "Kohaku just joined the team. Try and show some enthusiasm." I said, directing the attention to the small white tiger I had been holding in my arms.

"I'm excited." She said. It was indeed Kohaku, but she had managed to turn herself smaller.

"Wait, that's Kohaku?" Rias asked in slight surprise. "Last time I saw Kohaku, they were huge. How'd it get so small?"

"Well..."

Flashback

As I finished up writing some more songs for the concert in the next few months, I felt my new familiar's presence nearby. Kohaku suddenly entered my room and sat down on.

"Master." They called.

"Yes? What can I do for you?" I ask curiously.

"I've been giving this some thought, and, with your permission, I request that I stay by your side at all times." They asked.

This defiantly threw me off guard a bit. I wouldn't mind it really, but walking around everywhere with a White Tiger would probably lead to some unwanted attention and lots more problems. And what about school? I can't just walk in with a giant cat into the building for some random reason, that'd be one hell of a mess.

"I mean, I don't mind it. But it'd be a real problem if I just go start walking around with a White Tiger everywhere."

Kohaku hummed for a moment, as if they her thinking. Suddenly, a buff of smoke appeared out of this air and Kohaku had changed. Once a vicious White Tiger, now looking like an adorable little kitten. Oh my God, it was about the cutest thing I had ever laid eyes upon in my whole life. I picked her up and stared at the White Tiger cub.

"You're small, fluffy and adorable now and I love it." I said with a straight face before hugging Kohaku close to me as I began cuddling it. "You're small, cute, and huggable now. You're like a plushie I can have snuggles with."

"M-Master, please!" Kohaku begged, wanting to be released.

"Oh! Sorry about that...By the way..." I quickly apologized before changing the subject. "I hope it's not rude to ask, but what are you. Like, are you a boy or a girl?"

"I'm a girl." She identified.

"Oh, neat." I stated, suddenly feeling a yawn emerge from my mouth. "Guess we should go to bed. Come on Kohaku, time for sleep." I said, putting her on my bed as I climbed into the covers. "You can sleep on the bed if you want, just don't sleep on my face please."

"Very well." Kohaku walked around the bed for a place to lay down for the night. She found a spot at the top left of my bed, right near my head. She curled up and her eyes began to grow weary. "Goodnight Master."

"Goodnight Kohaku." I bid before allowing sleep to take control of me.

Present

"So yeah, Kohaku can turn from an actual White Tiger into this adorable little ball of fluff and snuggles~!" I sang, nuzzling my face into Kohaku's fur.

"I see..." Rias then looked gloom once again.

"Okay for real, what's going on?" I asked once more.

Suddenly, out of no where, Asia sighed. "I hate to say, but I can't be enthusiastic about this. Not after what happened yesterday." She grimaced.

"For the record, if this hadn't been an order from the higher ups we never would've taken this job, especially after what happened yesterday." Rias added. "They're sending us to a slime researcher's castle..."

"How'd we get stuck with this crap?" Asked Koneko, who looked very displeased.

All three of them released a heavy sigh, signifying they're total disinterest in what was to come.

"Why do you hate slimes so much?" Asked Kohaku. "They aren't that dangerous are they?"

"You see, before we met you, we kinda had a bad run in with a bunch of slimes in the Familiar Forest. Some of them didn't take it too well...while some..." I looked over to Akeno who simply smiled and looked on as she always did, even humming a happy little tune as she did. "Didn't mind it so much. One of us even tried to make it their familiar, much to our dismay." I said with a sigh, remembering the stupid bullshit Issei tried to pull. "Actually, speaking of the perv, why isn't Issei here? Kiba too?"

"Kiba was booked for summon requests today and Issei's getting in some more practice." Rias informed.

"Practice? In what?" I asked.

"Everything." She said bluntly.

"Well okay then."

"In any case, I don't understand why we can't just let this be. None of these slimes have been active in the past decade." Koneko griped.

"My thoughts exactly, it's not like they'll attack anyone nearby anytime soon." Rias commented.

I have had enough of these girls complaining. We're on a job and we need to do it. And they need to be reminded that this was asked of us because it was deemed necessary by this archduke guy. I stood up, Kohaku still in my arms and I made my declaration. "Attack or not, people have had to live their lives in fear because of these damned things! The archduke obviously sees them as a potential threat and they wants us to get rid of them before anything happens! It's our job to fulfill our duties to keep the innocent people out of harm's way and keep them safe from any and all potential or current threats! Could we call ourselves protectors if we didn't do our duties? No we could not!" I gripped my hand, my fire of passion burned within my eyes.

"...We never called ourselves that." Rias said.

"Do we keep innocent people out of any dangers?" I asked.

"Of course."

"Then there you go." I said, sitting back down.

"I understand how you feel (Y/N), but I highly doubt this is all that important." Rias said.

"Okay, well what if the slimes were to attack later? We'd be the ones held responsible for not dealing with them in the first place!"

"My my, someone sure is passionate about his this job. It makes me wonder." Akeno looked at me with her curious magenta eyes, catching me off guard. "Would you have some kind of alterior motive in this mission?" She asked.

"Like what?" I asked, clearly confused.

"(Y/N)..." I hear Koneko call out, prompting me to look towards her. And she just glared at me, and those topaz eyes of hers practically killed me, as I could feel them burrow deep into my very soul. "You wouldn't be planning anything pervy, would you?" She practically hissed at me.

All I could do was sigh in response. "No, I'm not. Look, I know for a fact that all of you want to see these things burn as much as I do, but we were also assigned to bring back any research data we can find. So before we go on a full on murder fest, let's see what we can find before we destroy the damn place." 

"We're here." The carriage driver said.

I opened the door and hopped out with Kohaku, setting her down on the ground and looked at the castle. It didn't look half bad. Key word being 'half'. As in, 'half' of the castle was destroyed.

I helped the girls out of the carriage and we thank the driver for the ride as they head on back the way we came.

We all walked towards the castle and I opened the door, proceeding to enter. Upon entering, I look around and see that the castle was dark and cold, incredibly dusty and ruined. Multiple cracks in the walls and floor could immediately be seen. However, there were no signs of danger of any kind present.

"See? Looks kinda creepy but it's perfectly safe." I assure the uneasy girls. "So, let's go and find some sli-!" I was cut off by something hard and metallic sounding falling onto my head, causing me to hunch over in pain as I held my head.

"(Y/N)! Are you okay?" Asia asked as she rushed to my aid.

"I thought you said it would be safe in here." Koneko bickered.

"I did, and I meant it." I groaned as I reposition myself. "I'm totally fine." I said, shrugging off the pain.

"(Y/N), look! The basin!" Asia cried.

I looked down at what she and the others were staring at, only to see the silver basin morph into a silver slime. It quickly slithered away as fast as it could. "A slime?" I couldn't help but ask as I had felt a little baffled that there was a shape shifting slime.

"Yeah, but I've never heard of one transforming like that." Rias informed.

"Maybe the researcher here created it." Said Akeno.

"That seems like an odd thing to make." I inquired.

"The reports said that the researcher who lived here must be long dead now. But maybe he left some notes." Rias pondered.

"Well, the archduke wouldn't have asked us to retrieve any research material if there wasn't a slight possibility. Let's search some of the rooms down here and see what we can find. Anything useful looking; we snag and take it back." I suggest as I began walking to a nearby room.

I opened door after door and everything turned up unsuccessful. Every room we searched on the first floor was either empty or destroyed. But the last room we looked into was more promising, as I was finally met with a room that showed some promise. Two massive bookcases, filled to the brim with books. All of us enter the room and wandered around looking for anything. But, it didn't appear to be fruitful, as most of the books in the room appeared to be completely destroyed.

Asia reached for one of the book covers on the nearby table and opened it, only to see that all of the paged were missing. It had looked like they were removed in one way or another. "I think this may have been a book he wrote." She inquired. "But it looks like the pages were removed."

"I'm willing to bet that a slime might've eaten it. Look at the spines, the remaining pieces of the pages look like they were removed by force or melted." I said analytically.

"Oh hey, I found one still intact! Pages and everything!" Akeno cheered.

"Oh yeah?" I asked in slight surprise. I walked over to see what she had found, and it was indeed a book that was still intact with all of it's pages.

"I think it might've been a research journal or something. It seems to catalogue the various slimes he created."

"Sweet! There's some retrievable data right there!" I cheered happily. "We could also use that to figure out what we're up against when we encounter the different slimes through this busted up old castle." I suggest.

"We've seen every room here on the first floor, so let's head up stairs and see what else we can find." Asia chirped with a more happy attitude. I think the fact that we finally found something and haven't run into any of those clothes melting slimes are helping her feel a little bit better...Can't say for the other two though.

"No!" Rias and Koneko wept as they held onto each other as they cried. "Let's go home!"

"Are you kidding me?!" I asked in disbelief. "We finally just found a lead, we're not going home now. Come on! Lets finish the mission!" I cheered as I walked over to the door, immediately kicking it down and sending it flying off it's hinges. "King of Doors Bitch!" I hollered as I left the room to progress further.

As I walked onwards with Kohaku by my side and the girls right behind me, I could hear their chatter, and it wasn't very encouraging.

"That punk's got to be up to something." Koneko stated, getting Asia and Rias to agree.

"Oh my God! Is it really that hard to believe that I just want to finish the mission with great success?" I ask irritably. "I mean, God forbid I try and try and do a good job! Besides, what ever mission we're sent on I always enjoy them. I always see everything as experience."

"I...guess you have a point." Rias said, feeling slightly defeated.

We finally make our way back to the entrance of the castle and prepare to head up the stairs.

"(Y/N) look." Rias spoke worriedly.

I look over to her and she looked like she sounded, worried. I looked at to what she was looking at and instantly knew why. We met them again. "Damn, these things again?" I grimaced over the slight of the different sized green, clothes melting slimes we encountered in the Familiar Forest. It was bad enough dealing with those before, but now they're in different shapes and sizes now.

Rias instantly began to conjure her Ruin Fire, preparing to destroy the slimes, but with that much power she was building up she might even bring down the whole castle too.

"Master wait!" I plead, making her stop. "If you unleash that much power in here, you'll destroy the whole castle!"

Rias immediately looked regretful.

"Well why shouldn't we burn it down?!" Koneko complained.

"Because we're still in here?!" I replied. "Kohaku! You're up!" I ordered.

"Just leave it to me!" She said, summoning a large, thick gust of wind and reappearing as her true God Beast White Tiger form. "Here we go!" She let out a mighty and powerful roar, sending the slimes flying onto the wall on the other side of the room. However, it didn't seem to work in the slightest as the slimes just slid back down and onto the floor, all still in one peice.

"That didn't do anything! Your cat's useless!" Koneko chastised.

"These slimes must be super tough if they can withstand something like that." I said.

"Let's fall back! Retreat to the second floor!" Rias ordered and we all did as was instructed.

Once we managed to reach a high enough point of the stairs, I decided to look back at the slimes to see if we were being chased. But that wasn't the case, they slimes remained on the first floor, not making a single attempt to pursue us at all.

"That's odd, they're not following us." I inquired.

"Maybe they're bad at climbing?" Akeno suggested.

"I think it might be because we got out of their territory." I replied. "Maybe they're territorial?"

"What matters it were safe now." Rias stated confidently and full of relief. "Let's keep on moving people! The further we get away from those thing the-WOAH!" She yelped as she slipped onto the stone hard floor, now covered in some slimly liquid. "Ow, what he heck?!" She cried, suddenly feeling the liquid cover her right hand. "Ew, what it this stuff? And why is it so slimy?"

We all looked up and saw three large, grey colored slims on the second floor. They appeared to be secrete the slime out of their bodies, completely covering the stairs. 

"We're surrounded!" Asia cried worriedly.

"What the hell kind of slimes are those?" I asked.

"Hold on a sec, lemme look it up." Akeno said, flipping through the paged of the book we recovered from earlier. "Uh, says here they're lotion slimes. The book says that when in danger, their bodies secrete a vicious lubricating fluid. Though it feels rather nice on the skin...Still a failure." She informed. And that part got me intrigued.

"I wonder what he was trying to make. Very curious." Asia said quizzically.

"Yeah, it doesn't really sound like he was all that good at this stuff huh?" I ask, suddenly feeing being pulled down to the ground as I heard Rias yelp again as she slipped, bringing us all down with her in the process.

We all began to fall back down to the first floor, which was still covered with green slimes.

I was the last one to be pulled down, but I was saved by my familiar grabbing me by the collar of my blazer, causing Asia, who was holding onto me at the time, to lose her grip and fall with the girls down to the slime covered floor.

"Wow, you saved me. Thanks Kohaku!" I praised my familiar by petting her on the head and nuzzling her face.

"Apologies for missing the girls, Master." She said.

I quickly began to hear the girl bicker and struggle to get out of the pile of slimes around them, already melting their clothes once more.

"Oh shit! Hang on! I'll get you out of there!" I declare, quickly summoning Oath Maker into my hand and raising it into the air. "Kohaku, on my mark!" I order. "Now! Goddess Wind!" I chanted, as Kohaku and I unleash our mighty winds in unison, blowing away and shredding the slimes into pieces. Kohaku and I hop down from the higher level of the stairs and join the girls down before, only to watch as the slimes reconnect with each other and slither away with great haste. "Huh, so once they're outmatched they abandon their territory, interesting." I say before changing my attention to the girls. "Hey you girls okay?" I asked before I felt my face flared up from the sight I had been bared witness to.

"Oh no, I really liked this outfit." Asia whined as she covered her revealed parts of her holy sister outfit she wore.

"Those gross slimes melted more then half my skirt off again." Rias complained as she covered her bare chest and her released lower region.

"Oh my, what naughty slimes." Akeno sang with her usual smile, not even trying to cover up her showing underwear. "Melting my clothes, right down to my underwear. What's a girl to do?"

"...Gross. Now I'm all slimy and my clothes are melted and wet." Koneko sneered as she tried covering herself. She soon looked over at me and she immediately got mad at the fact that I was staring.

I couldn't help it, something within me was telling me not to look away. I felt so disgusted with myself, but those images would forever be burned into my brain.

"Pervert!" She shouted, rushing at me with full force, pure killing instinct was easily detectable from this girl.

"Wait! Hold on! I'm sorry! I didn't mean to!" I begged, but still received a fist to the gut, knocking the air out of my body as I fell to the ground in pain.

"(Y/N)!" Asia cried, rushing over to me.

"Stupid (Y/N)." Rias mumbled as she blushed.

"My my, what a naughty boy (Y/N) really is. I guess he is at that age though, it should only be natural he'd be interested in girls~." Akeno sang with pure delight.

"Not...Helping..." I groaned, trying to get Akeno to stop with the teasing.

Time Skip

The girls managed to find something to cover themselves and we proceeded through the castle's second floor. Rias and Koneko still seemed mad at me even though I apologized, but Asia was more concerned for my well being than hers, and Akeno just kept teasing me about the whole thing.

"Next time we see a green slime, we crush it without hesitation." Rias ordered.

"Can we use (Y/N)'s body?" Koneko asked.

"I don't see why not." She said.

"Come on! I said I was sorry, what more do you want from me?!" I pleaded. "But in all seriousness, it seems like whoever this slime researcher was, he was trying to make one slime in particular but ended up mass producing a bunch of random ones in the process." I wondered.

"Seems like it." Akeno agreed, reading more into the research book we found. "He writes that it's impossible to tell what trait a slime might have before creating it." She informed.

"When we're done here, let's destroy this castle. Burn it. Purify the land." Rias said with anger.

"That does seem like the thing to do, but I'm not sure how the authorities would feel about it." Asia said.

"This fortress has been abandoned for some time, so I highly doubt anyone would care." Rias added.

"As much as I enjoy burning down buildings as much as the next guy, I still feel like we shouldn't risk it." I claimed with a slight hint of worry.

We finally come to a stop and see a hallway with some statues standing on both sides of the hall, all of them having rather large breasts.

"A scientist lived here huh?" Koneko bickered as she stared at the more developed statues.

"Why? Is something odd about them?" I asked, clearly worried that one more wrong move could send my underclassmen off the deep end.

However, upon closer inspection, I thought I saw something very bizarre. One of the chests of the statues moved. I honestly thought my mind was playing tricks on me.

"What's wrong? Did you see something (Y/N)?" Rias asked.

"Yeah, I think so. It looks like one of their chests moved."

I could tell everyone didn't believe me as they all gasped in doubt, I could feel their unbelieving eyes dig into my back.

"Did you really just say that? Honestly, you're spending way too much time around that pervert." Koneko jeered.

"Look, while I might agree I may be spending too much time around Issei, I'm serious when I say it moved." I replied. "Look, I'll show you." I said as I walked up to the statue in question and gave the chest a light poke with my finger, it immediately sunk in and bounced off. "Wow, it's so squishy!" I claim, causing the girls gasp in utter surprise. I placed my whole and onto it and continued to squeeze it. To be honest, it was kinda fun and stress relieving. Like squeezing a stress ball. "It's so squishy, but really firm at the same time." I claim.

Once I let go, the breasts of the statue drooped off the chest and fell to the ground. I actually screamed a bit when I saw this.

They quickly turn from their stone color to a more pinkish red hue.

"Bust Slimes, they attach to women's chests and mimic them. Apparently, their preference is to accentuate smaller breasts. Failed again, but I'm close." Akeno read from the book.

"CLOSE TO WHAT?!" I asked furiously.

The slimes suddenly jumped off the ground and headed straight for Koneko. She glared at them and she punched them into millions of pieces and fall to the floor.

"I'll grow..." Koneko murmurs. "I'm still developing right now." She adds.

"Oh...um...okay." I sputtered.

We all continued on our way through the castle and eventually found a room were we could take refuge for a bit.

"Good, this room looks safe at least. Why don't we take a little break here and catch our breaths?" I ask, but suddenly get hit with a horrid stench of death in the air, I nearly gag as the smell finally hit me. "Gah! Oh God! Never mind! Maybe we should try another room! What the hell smells so ba-" I immediately found the source. A rotting skeleton sitting on the couch at the other end of the room. "...Never mind, found out where the smell was coming from." I said boredly.

Rias casted a spell and made the stench go away almost instantly. How convenient.

"Ah, finally! Thanks Master." I thanked my master. "Well, I don't know about you girls, but I'm willing to bet that this is the Slime Researcher." I said. I then noticed a book on a nearby table, still looking completely intact. "Oh hey, another book!" I exclaimed as I flipped through the pages, only to find them all blank. Except for one in the middle. "Let's see here, 'It's finished. After years of work, I've fulfilled mankind's greatest dream. Now I can die without regret. Yes, I see heaven's light'...The fuck is this?"

"(Y/N)! Look! Over There!" Asia shouted as more slimes popped up out of nowhere and began to change their shape.

"They're transforming, but into what?" Rias questioned anxiously.

After a few more moments, the slimes turned into naked copies of Rias and the girls.

"WHAT THE HELL?!"

Rias, Asia and Koneko scream in embarrassment and Akeno only giggled.

Once again, I couldn't help but stare. My face flared up again. As to why I don't know.

"(Y/N)! Please don't look! I-It's not right this way!" Asia pleaded as she covered my eyes.

"Covering his eyes isn't enough Asia! We have to turn his head too!" Rias said, grabbing my head and forcefully turning it away. "In any other circumstance I wouldn't mind you seeing me naked, but not like this!"

"WHAT?!" I shouted, before being slammed in the head hard by a powerful fist, I'm assuming Koneko, sending me to the ground.

"My my, you really are a naughty boy aren't you (Y/N)~?" Akeno giggled.

"Please stop..." I groaned.

Time Skip

Before I knew what was even going on anymore, we were all outside watching the Slime Castle burn down in a beautiful blazing inferno. It's cinders flying into the night sky as the flames grew bigger, brighter, and much stronger.

"The land is pure." Rias states.

"Indeed, pure." Asia agreed.

"Pure as a lamb now." Koneko added.

"A roasted lamb." They all said in unison.

"Oh my, so scary you girls look." Akeno giggled, watching the girls as they all watched the castle burn to the ground.

So, our mission ends here. Apparently, the greatest dream of mankind that guy wrote about was apparently to enjoy the services of a harem of naked slime ladies...So fucking weird. "Well, thank God Issei wasn't here today, otherwise he'd try and stop us from doing this for sure." I inquired with a defeated laugh.

"Master." Kohaku called.

"Yes?"

"If you wouldn't mind, I'd very much like to explore a human city if it's okay." She asked.

It certainly took me by surprise, her request. But seeing after all she did today, I believe she earned some sort of reward. I smiled and pet her on her head. "Sure, let's head into town next chance we get so you can get familiar with the area. But, first thing's first...Pervy slime dude...rest in peace, for your dream has come true."