Kidou Senshi SD Gundam no Gyakushuu

機動戦士ＳＤガンダムの逆襲

It consists of two parts:

#1: "The Storm-Calling School Festival" - Char and Haman host a festival to celebrate the union between the Nu School for Boys and the Zeta School for Girls. But all hell breaks loose when the Counterattack School gang - led by Amuro, Judau and Kamille - rush in to crash the party.

#2: "The Tale of the SD Warring States: The Chapter of the Violent Final Sky Castle".