This is the best pairing, because Medicine is a poison doll, but she's always so cheery around Yuuka. Their themes match up so elegantly, and the age-gap is delicious.
Spent ten minutes trying to come up with some sort of punny comment. Somehow, the fact that I had a Thomas the Tank Engine book memorized as a kid makes this exponentially more painful.
Is there something beyond just two girls cutely brushing each other's teeth here? I suppose it's a meme or whatever, but is there additional context which makes people feel it's weird that I'm not aware of?