Riko, a female student, an older brother-in-law, and a plain NEET man... Two people suddenly end up living in the same house under one roof when their parents remarry. Her dull older brother Niriko, who suddenly started living together with her, is at a loss. Riko is forced to have sex with her hidden electric massager and masturbation in her room for 3 days on a couple trip. However, there was an unexpected coincidence between the two... Riko and my brother's sex compatibility was really the best. My rebellious tsundere sister gets squid by her disliked brother-in-law SSIS-471 SSIS471 SSIS