Sei Toudou

Birthdate: June 15, 1984
Height: 183cm
Blood type: A

Sei is one of Ichika's tutors and a high school student. He instructs her in grammar, literature, and social sciences. He is introduced as the twin brother of Kai. Of the two, Sei usually seems to be the calmer, gentler one. Ichika has developed romantic feelings for him.

(Source: Wikipedia)