Since entering high school, Kyou Nukui has skipped every class. He spends his days shut in his bedroom composing music and uploading it online, accompanied by illustrations from his only friend, an artist who goes by the pseudonym "Kiriyume." One day, Kyou hesitantly uploads his newest composition, TR03, which marks his first departure from his usual style. He also does not post it under his typical handle "HibikiP," but simply as "me," and without a drawing from his mysterious friend.
Shortly after, Kyou receives a very polite email that not only praises his music but also somehow identifies him as the composer behind TR03. The email also requests a meeting at a nearby park, which he cautiously decides to attend. To his surprise, however, he finds three elementary school girls waiting at the meeting spot! Suddenly, Jun Gotou, Nozomi Momijidani, and Sora Kaneshiro ask for his help in holding a concert at their home, an old church now used as an orphanage. Though reluctant at first, after witnessing their musical abilities, Kyou eventually agrees to their proposal.
Based on the award-winning light novel series by Sagu Aoyama, Tenshi no 3P! follows Kyou as these three angels change his life.