Yeah like, what's the problem with that¿
Just visiting, metting everyone, explain and goodbye lol
Because caius and kouichi seem to be so bothered by it, I think it’s a case of “once you go back you can’t return” thing. I’m not sure though-
Also some people believe that kouichi could be dead due to him being teleported to caius’s world. I think that he might have lied to the Male about going back because he believed he would be able to make the other fall in love with him. Which did work. So kouichi might not even be able to go back anyway
Maybe, instead of leaving Caius forever, he can just visit. Or he could take Caius with him and introduce him to his friends (idk if that's possible though I can't remember if they said that Caius wouldn't be able to leave)