While his actual age is unknown, Sakuya is physically 15 years old. He has green hair and often wears green clothing. His eyes are red as a result of becoming a vampire. He is often seen wearing his pink headphones.
By his classmates, Sakuya is known as the class clown, as he is always making jokes and telling rumors of nearby vampires in an effort to scare his friends. The only friend who knows his true identity, however, is Mahiru.
Sakuya is shown feeling a conflicting loyalty between Mahiru and Tsubaki. He will not betray Tsubaki because he knows that Tsubaki will not betray him. Sakuya is shown to be quite upset upon finding out Mahiru had been lying to him and pretended to hate Mahiru in an attempt to get Mahiru to kill him.
During his childhood, Sakuya's older sister was driven to suicide by their parents, who said was an accident to the police in order to receive money of their daughter's life insurance. Sakuya knew the truth but was forced to lie about the situation, which was also his first of many lies. Before her death, Sakuya's sister made their parents promise not to hurt her little brother. While in his adolescence, Sakuya suffered the same fate as his sister. After this occurred, Tsubaki made Sakuya a vampire and one of his subclass.
- Unlike normal subclass, Sakuya is capable of being out in sunlight without being harmed due to being one of Tsubaki's subclass.
- Strength: 7/10
- Tactics: 6/10
- Cooperativeness: 3/10
- Mental: 6/10
- Appearance: 6/10
- Negativity: 10/10
- "I was born in a town of liars, as a child of liars. A year ago I sneaked into a middle school to kill time, but in truth I probably wished for something else. [...] Just like that, because of that hand and that voice, I thought... "Man, I'd love to be friends with this guy." Mahiru... thank you for finding me... thank you for reaching out to me...!" (About Mahiru Shirota)
- "So... how much of what I said was a lie?"
- Sakuya's favourite dish is Okonomiyaki (お好み焼き).
- He dislikes lies and liars.
- His hobbies are browsing through music shops and playing rhythm games.
- His best subject is math.
- His worst subject is ethics and Japanese (especially modern Japanese).
- His favorite color is firefly green.
- The stripes on his jacket are firefly green.
- He is sometimes seen with pink headphones.
- In the drama CD "The vampire-only summer vacation" Sakuya admits that he'd like to be called "Sakkun".
- In the first popularity poll he came third with 2000 votes.
- He gets envious of anyone that calls themselves Mahiru's friend.
- His zodiac sign is Aries.
- His favorite drink is carbonated drinks.
- He did not participate in any club activities while he was in school.