A new idol and composer!

Shining Saotome hears about Yuki Luna's songs. He discovers Luna's musical talent for composing and singing. He invites her to Shining Agency where Luna meets STARISH, and Quartet night. But what's this? Luna actually composed Poison Kiss for Quartet Night! Soon all the boys start falling for this new girl! STARISH x OC, Quartet Night x OC, and Heavens x OC! Who will Luna choose?