Natsuki sets his heart on creating a tidal power generator that utilizes the ebb and flow of the ocean's tides. He dives back into the ocean to find some materials and salvages some resin from the ruins of Ryuuji's family's factory. As soon as he gets back he gets to work. As they are working, Natsuki and Ryuuji exchange heated opinions over how the generator should be built. Atri intervenes and the two guys become closer friends. Meanwhile, a suspicious-looking character peeks at them from outside of the school....
Jeez... First, you're calm, then you get all 
heated, and then apologize outta nowhere.
بئساً... في البداية كنتَ هادئاً، ثمّ تنفعل
وتعتذر بشكل مُفاجئ
Meine Fresse …
Por Dios…
Por Dios…
Je suis perdu. D’abord, t’es calme,
puis tu cries, et enfin, tu t’excuses.
Che diamine...
Vou te contar, viu?
Ну и ну, то орёт, то молчит,
то вдруг извиняется.
ให้ตายเถอะ