Because of her father's remarriage, the sixteen-year-old high school girl Asahina Ema (voiced by Sato Rina) moved into the Asahina family, and she suddenly had thirteen new brothers! Her father and new mother lived elsewhere, while Ema and her thirteen brothers lived under the same roof. On the first day of her new life, Ema was greeted by the gentle eldest son Masami and the young youngest son Miya. Then Ema met her new brothers one by one, including the identical twins Tsubaki (voiced by Suzumura Kenichi) and Azusa (voiced by Toriumi Hirosuke), and she also found that her classmate Asahina Yuusuke (voiced by Hosoya Yoshimasa) had also become her brother. Yuusuke was very surprised by Ema's arrival, and he seemed to have an unusual feeling for Ema. The thirteen brothers have different professions and personalities. Will Ema's arrival cause them trouble? Ang (voiced by Ono Daisuke), who celebrated his twentieth birthday, actually spoke his heart out after drinking... What kind of bond will Ema, who hopes to be accepted one day, have with the thirteen brothers?