Yatsugaike ~Yatsugaike Kitan~

Main character is born in a military officer family. He's a shy boy and currently lives alone due to family circumstances. One day he witnesses sexual assault in the park, tries to help and gets murdered as a result. He awakens as a spirit. He can't affect the world except for when in situation that caused his death. He can materialize only when insulting girls in the park...

[From vndbreview]