[Imagawa YO-JIN] Leave it to onii-chan Chapters 1-4 {WitzMacher}

Runa is a bratty little sister who has her big brother groveling at her feet, but the family dynamic curdles fast when a compromising photograph hands him all the leverage he needs. What begins as sibling bickering spirals into coerced encounters where her protests of being family go ignored—and things turn darker still when another girl is bound, collared, and held down while a smiling accomplice cheerfully offers up her helpless friend. Blackmail, betrayal, and shattered taboos fuel this four-chapter descent into a household where nobody is safe from onii-chan.