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....
Honestly... I thought I had no 
choice but to do this on my own.
بصراحة... ارتأيتُ بأنّني لا أملك
خياراً سوى فعل هذا بمفردي سابقاً
Ursprünglich dachte ich,
ich müsste das alles allein durchziehen.
Sinceramente pensaba
que tendría que hacerlo solo.
Sinceramente pensaba
que tendría que hacerlo solo.
À l’origine,
je comptais m’en occuper tout seul.
Sinceramente, credevo
di dover fare tutto da solo.
Para ser sincero, eu achava que
ia ter que fazer isso sozinho.
Честно говоря, я думал,
придётся работать одному.