Showerthought: Unless Kouki is unfathomably based, the most Yui would get in her route would be a kiss
Unless Kouki is unfathomably based, Cryska will still be the true winner of Total Eclipse as she'd be the only one to get laid.
I bet Kouki no balls, no way he has Yui go full incest mode.
Well even if Yui and Yuuya didn't have sex in the Yui route, as consolation, there's always the Strike Frontier H-scenes where Yuuya essentially slept with every single girl in TE.