The young man Nake is always annoyed every time he meets his uncle even though the boy does not show his face, the main reason is because the uncle married a young and beautiful wife and.... very good at sex (he knew it from sneaking peeks at his wife many times).
Nake wished to have a "rain cloud" with Takase, which seemed far-fetched, but it turned out to be very easy. Takase took the initiative to secretly have sex with Nake, perhaps she knew what her grandson wanted and perhaps Takase was also tired of "having sex" with her husband.
And in that house, the two nieces secretly fucked each other for a long time without anyone knowing....