Ema Hinata is a sweet girl with only her father to call family. One day, she learns that he will be remarrying Miwa Asahina, a wealthy fashion designer. Though she's glad she has a new place to call home, the family she gains is greater than she could ever imagine—Ema now has 13 step-brothers!

Wishing to give her father space, she moves into the Sunrise Residence where her brothers live. As she settles in, Ema realizes she may not experience the loving kinship of a family that she has always longed for, as many of her new brothers exhibit feelings toward Ema that aren't just familial.

With each brother desiring Ema's attention in his own way, will she be able to work toward a happy ending for all, or will she choose one brother that has stolen her heart?

Idea Factory released two games based on the franchise for the Sony PlayStation Portable. A compilation of short stories that were first featured in Dengeki Girl’s Style and Sylph was also released.