poison girl, meet bombs girl, specifically by bombs girl eating poison and saying that maomao has ten minutes to diagnose her and figure out the antidote or else bombs girl dies,

It's not a bluff, and after confirming her identity Fuyumura would try and blackmail Maomao into helping her investigate her friend's disappearance (and Santa, Santa is also important), at which point Maomao can suggest that Fuyumura join the Crimson Corsairs instead of blowing Maomao's cover. Everybody wins, except Maomao, since Fuyumura would refuse to let go of the "help me find my friend and also Santa" thing and glom onto her