Kaidou

A manga only character, he only appears in the prologue. Kaido is Utena's best friend and classmate who also harbors romantic feelings for her. He defends her choice of uniform, saying it looks good on her, and follows her when she takes unusual routes from school to home. When Utena reveals her belief in "Mr. Licky-Lick" (Dios) based on her childhood experience and mysterious post cards she's received in the mail, Kaido doesn't believe her and sets out to disprove Dios's existence. At first, he argues that the postcards were sent by Utena's aunt to comfort her. However, after Utena falls into the river to rescue a child, Kaido sees a manifestation of Dios for himself. He then reveals the secret in the postcards: when assembled, the pictures on each of them form Ohtori Academy. It is thanks to Kaido's research that Utena transfers to Ohtori. Source: Wikipedia