How unlock Kizaki Shuuhei Events?

[Antera]

I only found him at school once. after that he is nowhere

[dsrpt.us]

I found him in an alley next to the clothes store.

[dsrpt.us]

I also noticed in his house there is a thing that will tell you where he is.

[Rukyaa]

after the alley he is at the karaoke, then again karaoke x2, then his school, then his home, his school, his home, his school.

After that, i can't help but it seem there is more after this. But i didn't find where. I just know there is still some more "???" in the CG galery

[Werewolverine4]

You're gonna need to purchase the B!tch in heat outfit and visit his room again.