Luka Urushibara

Ruka Urushibara (漆原るか, Urushibara Ruka) is a bishōnen who looks strikingly like a girl and even wears the garment of a miko despite being a boy. He is a close friend and classmate of Mayuri and is often asked by her to try on her cosplay costumes, usually declining to do so due to his shy nature. He has romantic feelings for Rintarou because he was there to protect him from an intimidating group of Otaku that wanted to take photos in the past, stating that it doesn't matter if he is a boy or a girl. However, Ruka hides these feelings because he is a boy and he knows Rintarou would never return these feelings.

Due to Okabe's intervention in the form of a message sent into the past to Ruka's mother, Ruka experiences being a girl until he decided to return to being a boy after witnessing the consequences of her wish of being a girl. Rukako was his name during his time as a girl.