(It seems that) She's not quite ready to take (drink) it black.
People who have followed this series may remember that little KC Kaga isn't the first shipgirl who Taisa has had asking Bismarck for black coffee only to find out how bitter it is. That would be Amagi-chan in post #5556416 (later revisited in post #6271145, which also incorporates post #5079833).
There's a lot to unpack in this series of images. Blondie seems awfully touchy-feely with Blindy, as if protective or uneasy. Why is the dog trying to pull her away? And why is this scenario in black and white? It almost seems like a dream sequence.
The translator's note on the bowl makes this funnier. For Marisa, a traditional home meal would be mushrooms and mystery meat, and I'm pretty sure Mima would encourage criminal acts.