Among the world Issei visited in the past one of them had the magic system that uses tier. It began from 1st tier to 11th tier or otherwise called Super-tier magic. Issei had learn this magic researching the wide array of spells and magic.
He only manage to learn few hundred but was able to create his own by trial and error. The reason why he hasn't use Tier magic was because his power was in an unstable state if he were to try to use foreign magic in his world then it might cause unforeseen catastrophe.
[A/N: it is not one to one with the overlord tier system]
Nevertheless, Now that reach Low god class and slowly regaining his prime. The reason it being mention is due Issei was now going to restore the memory of his lover by removing the things that would cause trouble.
"I didn't expect to do this but all of you deserve the real truth now."
Issei who was in the living room with his lovers who were looking at Irene beaming in jealousy. She kept giving teasing smile that infuriate Rias but Issei flick to stop causing a pout.
"Tell me Issei what is that your not telling us?"
"I was afraid telling the entire truth of who I am would harm you but….all of you deserve to know a bit of it."
Issei voice was quivering from both in excitement and worry that taken aback by his lovers. He was hesitant but felt it was the right thing to did since he can. Irene held his hand claiming him down while looked at Rias who was concern as if not wanting to force him but he only sighs then a massive amount of mana in the surroundings swirl around Issei that resulted in shock.
The mana was unbelievably enormous that it could only be compared to an ocean. Fortunately, Issei spend his time creating a power full barrier that distort his location or I would cause all faction to come to him.
Issei overall power would be Low primordial God if you add the tier magic he accumulated and the ever-growing Angel and true Maou power.
"Super-Tier magic: Life divination."
Every one of them groins in pain as Issei manipulates their psyche and bewildered to find the previous timeline memory. He had already guessed that Big G had long planted them.
Issei was unsure why he had done so and not just save them but nothing would change if he became mad as long they were alright. He wasn't able to revive them because of their soul being chatted by the outer gods but now regain hope.
He took his time to remove all information about the outer gods was eroding their souls. Thankfully Big G place countless seal comparable to Trihexa.
It took him a whole decade in mental years but only a few hours in real-time to remove every single trace of the pesky outer God and placing a false image of them.
The reason he decided to show them a bit of the truth was that he had regained a bit of his power back allowing him to make sure the outer God wouldn't be able to cause harm.
Their body twitches from the flashes of memory that had yet to happen. All of them excluding Asia had tears streaming down their face. They turn to look at Issei heartbroken then Ran up to him.
""Issei/Darling/Ise!!""
Hearing their words that full of love and passion cause his heart to finally shatter cried his heart out from their loving embrace while Irene smiled deciding to go and where Issei other lover helping him to restore their memory. She teleported back to where Valerie and Ingvild was then restore their memories of the past but doing the same as Issei.
Irene didn't go restore Irina and Xenovia until they visit Kuoh meanwhile she went to Kyoto restoring Kunou and Yasaka memories then to the Sitri heiress and a certain perverted girl.
Thankfully, She was linked to Issei allowing her to use his power. Currently, her and Albion's power became higher than their prime making them D-Ranked High Primordial God class.
Back to Issei, They finally calm down while Issei was constantly smiling seeing them again. Though All of them were annoyed that Issei kept them waiting but only warily smile in response.
"I can't believe you came back to the past to save again Issei."
"Issei-senpai…..did nee-san."
"Ara~ did Kuroka-chan gotten his way issei first?"
"I-Issei you promise I will next."(Asia)
"Hey since we are all here do you guys want massive orgy?"
"Yuumi is such perv~. Well darling let's head to bed!"
"Hold on wait! Can we do it after we defeat Raiser."
"Gaaah it's frustrating I had to go again and face that guy. *sigh* at least I can finish him myself this time."
"Wait I'll tell you guys what I'm been up to."
Issei then began to explained everything about Murayama and saving Valerie along with awakening Ingvild. They nodded from his action though it meant Issei lovers kept increasing. He also told about Vali gaining her memory along with Albion and Irene gaining their body.
Rias accepted in providing ways for both of them to go on Kuoh academy. Though they need to hide about Ingvild Identity which Issei suggested in placing an alias. The old and new devil faction are currently at odds with another therefore they need to act carefully.
Afterward, They decided to head to bed but this time all of them join in with Issei. He kept smiling feeling the warmth of their body. Of course, Irene returns to join in the cuddling. Nothing illicit had happened as they enjoy the night sleeping.
The few days, Aika, Ingvild, and Valerie cried when Issei arrive along with the ORC. They told him about regaining their memory which shocked him but one glances to Irene gave the answer.
He glad she did as it became easier to get along with them. However, Katase and Murayama were jealous with the latter more than the former.
Vali, Albion and Kuroka arrive with the latter also regain her memory. Issei is worried that it would let the outer God increase their influence but nothing had yet happened. He decided to create a powerful ring for all his woman to avoid the outer gods.
Murayama and Katase were surprise that the Kuoh goddesses are devils but they quickly accepted it. However, having found out the prince of kuoh shook them to the core. It took them a while to recover then join in the training grounds. Koneko and Kuroka chatted with each other as they went to begin training.
They grew stronger for the past few days with Rias and Akeno having the overall pclass and S-ranked High class devil while Yuumi and Koneko A-ranked High class then finally Asia who was C-Ranked High class devil.
All of them had each of them began training not for Raiser the poor guy but the enemy they'll face in the future. They didn't want to be a burden to Issei.
Watching his lovers dedication made him smile then turn his attention to Aika who had became proficient in using magic and other spell. She was surprisingly better than any magic prodigy which made Issei question about it.
She wasn't this great in the previous timeline. Issei knew something within her was helping to grow stronger. The strongest attribute in magic she was capable of, was dark and curse magic.
At most her power was at D ranked low class devil in her current ability but it would be higher once she train more. Meanwhile, Murayama was getting better control over her sacred gear able to move in tremendous speed becoming as fast as sound.
She was learning to fight with her legs and becoming stronger. Her overall power is B ranked middle class devil. Finally, Katase who was learning magic but not at Aika's level and focus more in using a sword.
She was weak but refused to be left behind her friends and doesn't want her memory to erased. The only reason she was weak was because no one was teaching her swordsman. However, it was solve with the help of Yuumi who gladly train her.
_______________________________
Many days had past and the time of the rating games had begun or better yet butcher of fried chicken.
"Are you guys read to fried some Kentucky!?"
""YEAH!""