Tsumi to batsu: Uchuu no koukeisha2009

Kachi:
A tunnel in the ocean?

Isa Jo:
Yep. Turns out we were shot down over Fukuoka, Japan. There's a service tunnel here that should be free of enemies. Once we make it through, we'll infiltrate a floating air fortress. According to the database, a few ships are docked there. If we can get to one of those ships, we'll be home free.

Kachi:
And you're sure there are no enemies down here?

Isa Jo:
Positive. Why would enemies hang out in a water tunnel? Finally! There's the entrance!