Arata is very naive, Taichi at that time was a big a-hole. He and his classmate bullied Arata. Chihaya was the kindest of them all, so if she weren't in the class, Arata and Taichi would have never been friends. But the thoughts are beautiful, nonetheless. I think in their world now, they are very close friends who competed and played with each other for so long and that is the best kind of friends.