Riku Seya, usually referred to by his surname, is a classmate of Maho's who meets her when they enter junior high school.First introduced as Maho Nitori's classmate, he is a soft spoken and kind person.
Riku Seya initially takes an interest in Shuichi, whom he believes to have been born a girl, when they first meet. When he learns that Shuichi is was assigned male at birth, Seya becomes angry at Maho for hiding this, and stringing him along. But Riku soon reconciles with her and eventually starts dating her. Seya remains polite with Shuichi, though due to their initial meeting, there is always some awkwardness between the two. Later, he is shown to be very caring, as seen when he finds out about Nitori Shuuichi going to school dressed up in a girl's school uniform, and knowing the kind of pressure Maho and Shuichi are feeling because of that, so he tries to alleviate it.
He is first shown to be Maho's classmate, but as the series goes on, they become a official boyfriend and girlfriend couple. He is much more soft spoken to Maho, but is able to pick up on her feelings, especially when she is feeling the stress from Shuichi's incident when Shuichi one day dressed up as a girl to attend school. He tries his best to alleviate this by holding the same maid café at the school festival that they did the year before, but suggests that the cafe volunteer workers, instead, to do a gender bender maid cafe where the guys dress up as maids, and the girls dress up as the waiters/butlers.