乾 有彦

Shiki's classmate and best friend. When Shiki was living with the Arimas, he often used to hang out with Arihiko.

He has a competitive attitude against Shiki; Arihiko wants to get a girlfriend before Shiki does. Shiki cannot grasp how he became friends with Arihiko in the first place, since Shiki believes Arihiko has a "weird personality."