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....
This shaft is constantly 
going to be under pressure.
سيكون هذا العمود تحت الضّغط الدّائم
Damit erhöhst du die Last
auf die Drehachse hier.
Hay presión constante en ese eje.
Hay presión constante en ese eje.
L’axe supporterait trop de poids.
Quest'asse è continuamente sotto pressione.
Esse eixo fica carregado
de peso o tempo inteiro.
Эта ось постоянно нагружена.