Isami Fujiwara

Isami Fujiwara is Haruka's friend in the present timespace. He lives with his brother and grandmother, as their parents both died. He appears to be tough on the outside but has a fear for ghosts, and he is constantly nagging Yuu about being a "mama's boy" and never doing anything but studying and going to cram school. Yuu and Isami are very close, with Yuu's angsty, doubting nature offset by Isami's laid-back personality.

Isami is also friends with Ai, who has a secret crush on him. Isami does not seem interested at first, since he seems to prefer older women like his teacher. However, there are some hints that he may be growing interested in Ai by the end.

(Source: Wikipedia, edited)