Why coastal defense ships' rigging are only compatible with lesser-than-age-specific children, you ask?

Hmm... I am not the one who developed them, you see. It might involves a factor about the Abyssals...

Ah, there's this kind of story I've heard, you see.

The Abyssal Ships won't shoot at kids that have apparent ages like those of coastal defense ships, you know?

In the first place, this war began when humans killed an Abyssal Ship kid, wasn't it? It's their way of telling us that "we're different from you," I suppose?

Yuubari