Tsukimiya Ringo[]
He and Ringo are friends since they shared the same composer after Ringo had graduated from Saotome Academy and the latter's own composer was unable to write songs for him. He often finds Ringo's playful personality irritating.
Haruki Mori[]
Haruki Mori is Ringo and Ryuya's composer. Ringo's original composer was unable to write songs for Ringo because he didn't know whether to write for his female or male counterpart. Ringo managed to catch Shining Saotome in a trap and demanded that Haruki became his composer too. In the game, it's revealed Ryuya quit being an idol and singer because he blamed himself for Haruki's death. Haruki died from being hit by a car when he went back to get Ryuya's forgotten good luck charm before one of his singing events three years prior to Sweet Serenade. Ryuya and Ringo visit Haruki's grave alongside Haruka at the end of Sweet Serenade.
Hyuga Yamato[]
Ryuya's first younger brother. According to Ryuya's route in Utapri All Star, he said he has a younger brother but they're not that close. Ryuya said every time they see each other they always ended up fighting.
Hyuga Touma[]
Ryuya's second younger brother, he is always asking Ryuya if his body is okay.
Hyuga Makoto[]
Ryuya's third younger brother. 10 years younger than Ryuya, he always hugs Ryuya and beg for him to buy souvenirs for him.