Despite not being actual siblings, Yui has a profound affection for her "older brother," so when he ties the knot, she is devastated. At the wedding, Yui becomes acquainted with a disconsolate lad named Kaoru who happens to be in love with his cousin, who is marrying Yui's "brother." Seeking a new romance, Yui relocates to a boys' dormitory only to discover that Kaoru is the dorm's administrator!