Pita-Ten Vol 2

From the Tokyopop edition

Kotarou isn't too happy with the new development of Shia moving in with Misha. Despite his getting a mysterious headache every time he's near her, he can't help but feel sorry for her meager attempts at getting a job and he therefore helps her to find employment. Meanwhile, Takashi's safety is threatened by the sudden appearance of Hiroshi Mitarai, who is dead-set on avenging himself for the shame imposed upon him when Takashi scored higher then he did on the practice entrance exams.

Source: Anime News Network Encyclopedia