I had to re-read this. I'm not gonna lie when it comes to the relationship it's going to be with Mikoto. Not only is she confident in herself she is an open book, unlike Kokomi.
In the beginning, Saiki was an interest almost a game to her. As she tried to get his attention she did change a bit by becoming less shallow her development was nice, but as you keep reading Saiki treats her as a friend then she almost becomes a little sister someone to take care of. Most of the people that just see her for her looks and are after her innocents. Kokomi is someone who now needs to blossom. she needs to stop acting and yes she is beloved by God and the day she is her true self is the day her fated person will come.
Back to Mikoto, she knows Saiki's secret. she has seen the future with her soul mate. he even uses her for plans and tries to show Mikoto off to get Kokomi away. She has spent time with him regardless if it was for a bribe he encouraged it. Unlike with Kokomi every time he was with her it was because of her ...brother... or for some other reason. None of them were encouraged by him.
In the end, even if he doesn't get in a relationship with either I would be happy. He cares for both to an extent. He would support them later on.
This was so stupid to write but I like to write about characters from time to time.
Aki had the answer in the festival chapter why in the hell did he not pitch that again but to our two dear virgins!!! The hell Aki! Still love you tough. There is also the chance that Aki already knows who is going to be a top. He is a bottom and has plenty of experience with both genders. BTW i really thought for a sec that rock paper scissors was going to work. Not the first or the last time ive read an outcome like that.
so realistically this is possible. we can compare Caius le' pepe to a two liter bottle which is roughly the size of my thigh. Dath mammoth is the same size as kouichi's thigh. so he will be fine. at the end he'll be in bitch mode but that usually happens. (●'◡'●)ノ