1st story: Amatatsu is rivals with Sen, a popular guy in school. When he gets hit on the head with a baseball, he wakes up in a parallel universe where he and Sen are lovers! Absolutely love this story!
2nd story: voice fetish
3rd story: MC tells friend he is willing to be his wingman to help him get a girlfriend only to realize his own feeling for him!
4th story: wrestler body type fetish
I'm Banging My Rival From A Parallel World!?