CHILD'S PLAY! 
Someone (or something) is after Kogarashi, and it's up to the members of Yuragi-sou to protect him, each in their own special way. Can these romantic rivals work together? Suddenly, everyone except Yuuna is transformed into their child selves. As everyone loses their memories and Yuragi-sou falls into chaos...the assassin appears! But who is left to save Kogarashi?