AIKA and あつし are usually a close-knit ordinary sister and brother… but they have a secret. Driven by lust, they had sex once, and it was incredibly compatible, turning them into a pair that immediately has sex whenever they're alone! Even after having a pleasant conversation with their parents as a family, they immediately have sex when alone! Their compatibility is off the charts, and once started, they can't stop! The non-stop sister-brother sex is always at full throttle!
