Rin is a family of three with her husband and her husband's stepchild, Akira. Recently, however, her husband has been busy with work and not at her house, so Rin and Akira tend to continue living together. One day... when Akira was about to take a bath as usual, Rin was already there... And without noticing that Akira is watching, she starts masturbating by fingering her crotch.
