A member of SHIPS, as well as Kirarin's love interest. Throughout the beginning of the series, he seems oblivious to Kirarin's feelings, but by episode 12 he begins to portray feelings of jealousy over Hiroto's and Kirarin's friendly relationship. He is gentle and says very encouraging words to Kirari. Since he is as dense as her, he always has a calm and clueless expression. When he is wandering around in the city, he disguises himself as an otaku.

Name Origin: "hi" refers to the sun, "sei" refers to star