Age: 16-17
Birthday: June 20
Height: 174.1 cm
Blood type: B
Likes: manga, video games, anime, ice cream
Dislikes: keeping things clean, eggplant

Yuuki is the younger, less talkative twin. Like his older twin brother, he usually behaves in a very deadpan manner. Same as his brother Yuuta, he enjoys annoying Kaname with their constantly dry remarks. He has a hobby of reading manga and anime magazines; his favorite magazine is "Animeja." He played a numbers game which he called, "Mission," at a local game center and eventually became good at games. He is talented in many things, like cooking, Basketball and Judo, but he doesn't particularly enjoy any of them, only putting effort into things if there's something in it for him. He constantly makes trouble with his indifferent personality. When walking together, he will often rest his head on Yuuta's shoulder.

Although he tried to come off as indifferent, he opposed the idea of Yuuta getting a girlfriend. He's not particularly interested in either study and sport. His notes are always very close to the red-mark, which is only prevented by reading Yuuta's notes early in the mornings before exams. He's popular with girls, but has an awkward situation with them as he is weak to perfume and make-up scents, which make him nauseous. He was forced into joining the manga club by his friends. He is in the same class as Chizuru and Kaname. He seems to be aware that Chizuru likes Masaki. Chizuru calls him "Yukki."

He is interested in Kayo Sakura, who is known as the Cinderella of the cafeteria in his school.