Otousan ga Hayaku Shinimasu You ni.

Asuka and Hotaru are sisters living with their dad and are friendly with everyone in the neighborhood. Although they appear to be a healthy family without a mother, they have a secret that no one could tell. Asuka receives physical and sexual abuse from her father on a regular basis. Still, Asuka is desperate to protect her little sister from the same fate. However, her father's hand begins to be directed at the younger sister more and more... Asuka is cornered and needs to make a big decision!

(Source: Funguild, translated)