After defeating the veterans of Seiren Technical College, the Try Fighters win an easy victory in the third round, as their opponents self-destruct! With luck on their side, they are advancing to the quarterfinals. Fumina and the others observe the following match to see their next opponent. The victor of this match is Joto Middle School, which uses straight-assembled Gunpla but defeats a regularly winning team thanks to its fighters’ own control skills. After the match, two members of the Joto Middle School team beg the Try Fighters to let them win for the sake of their team leader Shimon Izuna’s little brother Mamoru, who is battling a serious illness. Fumina and the others are bewildered by this unexpected request, and begin to question their own reasons for fighting. In order to see the situation for himself and test his resolve, Sekai goes alone to the hospital where Shimon’s brother is being treated. Here, Sekai issues a straightforward declaration of war to Mamoru the Gunpla builder, and to his opponent Shimon!
強豪、成練高専に勝利し勢いに乗るトライファイターズは続く３回戦も対戦相手の自滅も手伝い快勝！ 運も味方に付け準々決勝へと駒を進める。次の対戦相手の視察の為、次の試合を見学するフミナたち。勝ち上がったのは、素組みのガンプラながらも持ち前の操縦技術で上位入賞の常連チームを敗った常冬中学だった。試合後、常冬中学のチームメイトたちから、難病と闘うチームリーダー、イズナ・シモンの弟、マモルの為に勝ちを譲って欲しいと嘆願される。突然の嘆願に困惑しながらも自らの戦う意味を問い思い悩むフミナたち。セカイは一人その真相と自分の覚悟を確かめる為、シモンの弟が入院している病院へと向かう…。そこで、セカイはガンプラを作ったマモルと対戦相手のシモンに対し正々堂々と宣戦布告をするのであった！
Try Fighters在接下来的第3场比赛中借着战胜强校，成练高职的势头乘胜追击，而对手的自我毁灭也助了一臂之力，他们最终得以胜出。运势当旺的Try Fighters继续向四分之一决赛进发。为了探查下一场的对手，文奈一行去观看接下来的比赛。最终胜出的常冬中学队伍尽管用的是素组的高达模型，但凭借着天生的操纵技术而打败了常胜热门队伍。赛后，常冬中学的队员为了和不治之症做抗争的，队长饭纲西门之弟，小守，而恳求文奈等人让赛，让常冬中学获胜。文奈他们为突然而来的恳求而为难，同时也因质问自身的战斗意义而头痛。世海为了弄清真相和自己的心意，只身一人前往西门弟弟所住的医院。在那儿，世海向制作高达模型的小守以及比赛对手的西门，堂堂正正地宣战。
