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....
I'm sure people came in submarines 
from the mainland and swiped them.
أنا متأكّد بأنّه أتى أشخاص بغوّاصات
من اليابسة الرّئيسيّة وسرقوها
Sie sind vom Festland mit Tauchbooten
gekommen und haben alles abgegrast.
Habrán enviado un submarino
del centro por ellas.
Habrán enviado un submarino
del centro a por ellas.
Des sous-marins de la métropole
ont dû venir se servir.
Dalla terraferma devono aver mandato
dei sommergibili per cercarle.
Devem ter vindo de submarino
do continente para levar todas.
Может, с большой земли
на подлодке за ними приплывали?
คงใช้เรือดำน้ำมางมเอาจากแผ่นดินใหญ่น่ะ