I wonder what the story behind this is. Gengetsu doesn't seem like the sort to care about anyone beyond herself, her sister, and her realm.

It's most likely that she is being nice to Koakuma be cause she can. It's got to be for a selfish reason.

HisRotundity said:

I wonder what the story behind this is. Gengetsu doesn't seem like the sort to care about anyone beyond herself, her sister, and her realm.

I've seen a couple doujins/fanworks where Koa is from Shinki's Makai / knows Alice from there or something like that.

Maybe this guy has some sort of similar connection between the dream realm thingy and Koa?

HisRotundity said:

I wonder what the story behind this is. Gengetsu doesn't seem like the sort to care about anyone beyond herself, her sister, and her realm.

Plot twist koa is her sister