YuruYuri: Happy Go Lily

Akari, Kyoko and Yui reminisce their childhood days when they were being bullied by a certain pink-haired girl. Later, a bump on the head causes Kyoko to become uncharacteristically polite. The others soon begin to miss the old Kyoko, especially when Kyoko plans to disband the Amusement Club, so they decide to hit her on the head again to return her to normal.