Ai is one of the possible love interests for Haruka in the game.
In the anime, Ai is show to be very interested in Haruka and the way her music affects himself and those around her. Over time, he becomes more curious about her because of how she speaks about people and their hearts. Eventually, he too finds himself attracted to her, though he doesn't understand why. When he sings her songs, he has stated that his heart "starts pounding." When Reiji lightly threatened STARISH with the possibility of QUARTET NIGHT taking her away from them, Ai was shown to agree; later asking him if he was serious about it.
In Season 4 Episode 1, after QUARTET NIGHT take Haruka away from HEAVENS, Ai holds her close and says that he wants "to feel their hearts beating together." He is then shocked when STARISH pulls her away from QUARTET NIGHT.