Having one sibling is fine but getting thirteen new siblings is a lot for Megumi to handle. Megumi's father is getting married to a woman who is the mother of thirteen sons. She never had brothers before so this will be Megumi's first time interacting with boys in a closer level. Megumi and her older sister Ema's lives are going to change when they step into that apartment. What's going to happen when her new siblings develop crushes on her? Who will fight and win Megumi's affection?