
I feel like what makes him like him so much is because he's known him for so long, and he tends to find the good sides in him sometimes which keeps Mori pretty happy. Plus, one chapter in the manga did show Mori before he met senpai. He was pretty wild after his relationship with Misaki went south. So he was hoping for someone to love. That's my opinion. ╮( ̄▽ ̄)╭

Exactly. I don't really like Challengers (poor graphics), but I really enjoy parts about Morinaga and senpai. And I love Koisuru... :)
It's been a long time since I read this, so I kind of forgot. But from what I remember, at the beginning of the story, Morinaga already like his senpai.
So what makes Morinaga like his senpai so much?