After Jeong Ihan's mother and brother died in a car crash when she was just 9 years old, she was raised by Han Chio and his parents, who lived next door. Now about to attend university, Ihan suddenly finds herself living with Chio under one roof, and she realizes that she feels more than just familial affection for her brother figure. While trying to deal with her trauma and the awkwardness of freshman life, Ihan meets Seo Yujin, a champion judoka at their university who is the spitting image of her late brother. And now he's moving in next door?!