Ruka Urushibara is a good friend and classmate of Mayuri and the protégé of Rintarou. While he may be appear to be feminine in appearance and character, Ruka is male. When Daru hacked into SERN’s database, Rintarou discovered that he needed an IBN 5100 to decode it. Fortunately for him, Ruka had an IBN 5100 stored in the family’s shrine.
Ruka is very emotional and sensitive. She is often startled to the point of crying by Rintarou’s comments but is just as driven when complimented by him. Rintarou points out how girly and hints some attraction towards Ruka but quickly dismisses it with “Even though he’s a boy”.
Ruka is attracted to Rintarou but has always held back because of the thought that he is male. There is one point that Ruka is turned into a female and even then, admits to Rintarou that she’d still love him even if she was male.
Despite being born as a male, Ruka has a very feminine appearance which causes him to get the attention of men (even Daru). He has well groomed hair, a gentle appearance, is very thin and is flat-chested. He likes to wear girl clothing (even at the shrine).
His shrine outfit has a white top with long, loose sleeves, a blood-red skirt, white socks and sandles with red straps. He wears a skull hair clip on the left side of his head.