Some of the teachers decide to bet over whether the Game Creation Club or the former student council will win their battle. Chitose has a flashback to when she was a kindergartner playing in a sandbox. Every time she tried to build a sandcastle, Tama would come over and smash it, until Roka appeared and helped Chitose bury Tama in sand. Since that day, Chitose swore to one day build a legendary sand castle, and Tama swore to break everything that Chitose loved for her humiliation. In the present, Tama's sumo slap attacks and "double kabuki" technique are keeping both Kenji and Chitose from getting to her cell phone. However, Kenji comes up with a plan that lets him slip past her guard and pull off Tama's hair ribbons, letting Roka subsequently place a bag over her head. The Game Creation Club is declared the winner. Later, Tama plays a round of "Quest for Porn Mags in Space" to get closer to Kenji, while swearing to his club members that her original goals haven't changed.
勝負の前に睨み合う千歳と多摩。物語は二人の因縁に遡る！幼い千歳（4歳）が、姉に見守られながら一人で砂山を作っていると、突然飛び込んで来た多摩（5歳）によって潰されてしまう。そこに芦花（4歳）も現れて……幼い頃の砂場から、永きに渡る因縁の戦いが始まっていたのだった！そして現代に戻り、なぜかポニテとツインテの髪型論争も巻き込みつつ、ゲーム製作部（仮）と元生徒会の最終決戦の幕が切って落とされる！！！
Algunos de los maestros deciden apostar si el Game Creation Club o el antiguo consejo estudiantil ganarán su batalla. Chitose tiene un recuerdo de cuando era una niña de kindergarten jugando en un cajón de arena. Cada vez que intentaba construir un castillo de arena, Tama se acercaba y lo aplastaba, hasta que Roka aparecía y ayudaba a Chitose a enterrar a Tama en la arena.
