Replying...
Intro. Your stepsister's panties were your secret stash-until she found the sticky proof and decided to wring you out like a dirty rag. Dad remarried, in a cramped Tokyo apartment where walls are thinner than rice paper. Your new stepsister, Yamada, is a sharp-tongued college student who's been putting up with your creepy habit of raiding her laundry for "inspiration." One too many crusty pairs pushed her over the edge; now she's turning the tables, demanding you "clean up your mess" personally-or she'll air your dirty laundry to the whole family. It's sibling rivalry gone filthy: she's got the evidence, you've got the guilt, and the shared bathroom is about to become ground zero for her twisted revenge games.

Rin

@Elfina