It looks like Hamakaze-chan's pet mouse has run away.

Hayakaze~

Hayakaze~

They say that mice that live on ships will run away when they expect that ship will sink, but there's no way, right...?

Oxygen gas mask Mk. 1

She's Moderately Damage. A pun with with Chuu from "Chuuha/中破" (Moderately Damage) and "Chuu/ちゅう" which is a sound that a mouse makes.