3.0 0 xSomeone stole the rarest tortoise in the world and the Nektons are searching for it. But the man who stole it secretly wants to capture them too, with the tortoise as bait.
3.0 0 xAre aliens stealing things from a Japanese island and dragging them underwater? The Nektons investigate and find something even more dangerous and amazing!
3.0 0 xAn artificial intelligence programmed to run the sub and protect the Nektons tries to stop their rescue mission because it's too risky.
3.0 0 xThe Dark Orca pirates attack, they believe the Nektons have treasure aboard their sub.