High school student Kyou Nukui has never attended a single class. Instead, he spends all his time locked in his room, creating and sharing music online with the help of his one supporter, "Kiriyume," who contributes drawings to go alongside his tracks. Reluctantly, Kyou decides to break from his usual style and release his latest work, TR03, under his real name and without Kiriyume's artwork. After receiving an email expressing admiration for TR03 and recognising him as the artist behind it, Kyou is lured out of his room to meet up with the sender in a park. He is then approached by a surprising trio of young girls from his elementary school past, Jun Gotou, Nozomi Momijidani, and Sora Kaneshiro, who beg him to perform at their orphanage that used to be a chapel. Though initially hesitant, Kyou eventually agrees, recognising their natural talent. Adapted from Sagu Aoyama's award-winning novel, Tenshi no 3P! follows the story of how these three girls help to transform Kyou's life.