The arena

"Lord Nato!"  a small kid called out as he ran to Nobu smiling, he seemed to be about 6 years old. He was a bit darker than the others and his low hair seemed a bit nappy. He wore a Kimono, most present did.

"Where's the fight happening? I don't know this arena your taking us to." The young boy said

"Of course you don't, the last battle that took place here was decades ago. Some don't speak of it because it was a terrifying experience. But in all truth it was a spectacle to watch. Not because it was a ding dong battle, there was an obvious strength gap between the two but the weaker fighter wouldn't stay down. He stood no matter how much damage he took." Nobu replied

"Woah! That sounds cool"

Nobu held his hand and they walked on.

"So who were they?  The kid asked

" My father and I"

"What? You fought your dad? Why?"

"Well, he said I wasn't ready and I was eager to prove myself. So I proposed we handled our disagreement like civilized men. With swords. Honestly I didn't expect to win, I just wanted to hurt him, I wanted to put up a good fight. Hopefully he would see my worth.  I put every ounce of myself into each swing of my Katana."

"What happened?"

Nobu stopped. 

"He cut my face open"

The boy was taken aback, there were many tales of how the Lord got his scar. Some were told as bedtime stories to small kids, others were meant to scare them into obedience. One such tale claimed he was born with it. It's said that he was a warrior before his birth and he was fighting demons on the other side to keep them from emerging with him. 

Another said he was wounded in a battle with the Tengu. But this small child never expected that an injury like that could've been inflicted by one's own father.

They were now close to the sea and the procession of about 15, 000 people slowly halted.  There was a descending path that wound down to the beach, to the left of it was a sharp rise where the earth bulged like a swollen stomach. Ten armoured samurai cleared a grassy area in front of the incline. They pulled two large chains that were hidden by the shrubs.  A wooden gate-like object about a hundred metres wide swung forward and fell before them with a resounding thud. It revealed a dark plummeting stairway, a few men went in first and lit torches along the Walls and ushered people in.

"Alright, off you go young one. Our paths are separate from here" Nobu smiled at the youngster

"It was a pleasure speaking with you my Lord" the boy bowed and ran to his older brother

"Gwyn, Nishi, with me" Nobu ordered.

Nobu, his children and few men walked along the path to the sea. When they were at the shore two large boats resembling canoes were brought to them. Nobu, Nishi and two men boarded one. And Gwyn, Apo and two men got in the other. They rowed smoothly along the water and were far out in no time.

"Hey Apo" Gwyn said softly

"You finally gonna teach me your 'secret hardening' technique."

"Sure. I don't think you'll be able to master it a couple seconds before a fight tho. It's very similar to multiplying your strength, but instead of storing energy inside you send it into your blade or whatever it is your hardening. The trick is not to try and force the energy, but let it flow, ease it along to it's destination."  Apo replied.

Gwyn glanced over at her father, who was talking to Nishi.  Was he getting advice too? She looked ahead to a small landmass.

"Hey pa" she called out. 

"Are we going to daisuke island."

"No, were pretty much where we're going."

"NOBU! Aah!!"  One of the men in his boat yelled,  he almost fell from the vessel, he lifted the oar he was using to show a large, growing piece of ice. Nobu leaned over the edge of the boat and looked at it's bottom below the surface. He saw a sheet of ice covering it, it too was slowly growing.

"What the hell? How's it freezing the water isn't even icy" Gwyn said

"Ya, the water is way below freezing but it never forms ice, whenever something touches it that thing might get frozen though. I have no clue why. Only a few creatures live in this region of water. Not a lot of them have evolved to withstand it" Apo said

The same man that called out to Nobu reached into the water. His oar fell because the ice made it heavy.

"Aaaah! " he pulled his hand back, it had a pale blue look to it.

"He finna die" Apo said

"He won't die it's just a bit of hypothermia" Nobu said

"Bring your hand here lemme cut it off before it spreads to the rest of your body" he continued as he drew his Kodachi.

"GwAaauhh!!!" The screaming intensified. 

"I'm joking,  Shi hihihhi" he laughed

"Get your ass some treatment" with that Nobu grabbed him and flung him all the way back to shore, he landed in the shallows, still screaming.

"Why's he screaming?" Nobu asked

"You threatened to cut his arm off then threw him overboard My Lord" the other man in the boat said. 

Nobu grabbed him and flung him too.

"The ice on the boats is increasing. We're slowly going under. Get rid of those two" Nobu told Apo.  He did as his Lord told him and soon only the four of them sat In the doomed boats.

"Is this why you called it 'sunken'? " Gwyn asked

"No, the entire area we are right now used to be above ground, over back at shore and the island used to be one thing, the sea was a lot further out. The last two who fought here permanently sunk a large portion of the earth including the arena." Apo responded

"Let's go" Nobu said, he grabbed Nishi and Apo grabbed Gwyn, they jumped into the water and swam down into the freezing depths.