ヒーローシンドローム

Main character is a second year high school student who always see mysterious fantasies during sex with girls. Sometimes it's a dark church, sometimes a sandy patio... and someone stands there, but illusion wears off as soon as he tries to remember the person. In order to solve this mystery he randomly invites girl to have an intercourse, and there is one special girl among them...

[From vndbreview]