十六岁的女高中生朝日奈绘麻因为父亲再婚入住了朝日奈家，这让她一下子就多出来了十三个兄弟，因为偶然的原因，父亲和母亲住在一起，日奈绘麻和十三个兄弟在一起生活。第一天，绘奈的松鼠朱莉就因为乱跑被兄弟们抓住。应届绘奈的是温柔的长男男雅臣和年幼的末子弥，还有一对双胞胎兄弟椿和梓，居然还有自己的同学日奈侑介，其他兄弟也因为绘麻的到来十分开心。侑介对绘麻的到来十分吃惊，因为他一直暗恋着绘麻。初来新家的绘麻因为发烧病倒了，身为兄弟的十三人轮流照顾她，这让一直缺少兄弟姐妹的爱的绘麻充满了期待。十三个兄弟的职业不同，性格也是各种各样的，绘麻的到来会给他们造成困扰还是开心？一切都未可知。这天是绘麻二十岁的生日，她竟然在酒后说出了自己的心里话。

Sixteen-year-old high school girl Asahina Ema moved into Asahina's house because her father remarried, which gave her thirteen more brothers at once , due to accidental reasons, father and mother live together, and Hina Ema lives with thirteen brothers. On the first day, Eina's squirrel Julie was caught by her brothers for running around. The graduating students of Eina are the gentle eldest boy Masami and the young Sukoya, as well as a pair of twin brothers Tsubaki and Azusa, and even their own classmate Hina Yusuke. The other brothers are also very happy because of Ema's arrival. Yusuke was very surprised by the arrival of Ema, because he has been secretly in love with Ema. Ema, who came to the new home for the first time, fell ill due to a fever, and the thirteen brothers took turns to take care of her. This made Ema, who had always lacked the love of brothers and sisters, full of expectations. The thirteen brothers have different occupations and different personalities. Will the arrival of Ema cause them trouble or happiness? Everything is unknown. This day is Ema's 20th birthday, and she actually spoke her mind after drinking