Kisaragi Aine (如月愛音) was once a famous idol with his partner, Onpa Kei and the best friend of Kotobuki Reiji. His only known relative is the professor which is also his uncle, who is currently taking care of his body.
From voice to looks he resembles Mikaze Ai exactly. From CGs, the only difference between Aine and Ai is their hair color, in which Aine's is a light brown rather than cyan. According to Haruka's dream in the game, Aine wears a necklace around his neck with a blue stone dangling from the chain.
In All Star, it was said that he was a famous idol and got tired of his life because of his hectic and busy schedule. He tried calling Reiji but he was busy at the moment because of his auditions. He thought of suicide and planned on drowning himself in the sea which ended as a failure since he was saved by his uncle (The professor). After his rescue, Aine is now in a coma and his uncle is currently taking care of him. In order to help Aine to wake up from his unconsciousness, his uncle decided to make a robot that looks exactly like him thus creating Mikaze Ai.