The person reflected in the mirror
An woman who was shunned because of her extremely pale skin since young, picked up a VERY well-behaved Reimu, and because of Reimu, got to befriend another woman with a Marisa. Then one day, her friend goes overseas, and she takes in Marisa.
Marisa is revealed to be scum, making rude declarations and such. It tries to refresh with Reimu, but when Reimu refuses, it injures Reimu severely. Despite that, Reimu doesn't blame Marisa, and tries to make up with Marisa. Marisa, refusing because the way Reimu phrased it made it sound like Marisa was at fault, kills Reimu.
Miss snaps, and tortures Marisa over and over in various ways with orange juice prolonging Marisa's suffering. She eventually beats Marisa to death. Enjoying the act of making scum suffer, she looks in the mirror to check her expression, and sees a woman whose white skin has turned black with bean paste, crying as she laughs.
Illustration: post #23520