Well, I tagged it as cum but ut might be anything. Mystia may also be a minigirl I don't know.

Ambiguous white fluid? Knowing what the bottle in the back is might help.

It's kefir. Retagging.

I like my Night Sparrow soaked with fermented milk, please.

Oh, so it was kefir all along!
Also, those two faces in the background are so darn awesome!