YuriTenshi said: ...Um, darkness? How is this not chocolate?
1) No tag about chocolate.
2) It's pure dark, to the shiny point. If you look for chocolate, no matter how dark it is, it's always brownish. This is ink black.
3) If you pay attention, the "darkness" liquid thingy is making her clothes.
4) Tags and what the artist (with google translate) says is that he actually wanted to do something like liquid thingy, and one tag is for when people do "odd" things.
Someone who actually knows japanese might be able to confirm, but the first thing i thought it was "darkness" as in chocolate bath, instead of chocolate, something odd but in a way clever.