Suzaki Madoka has been sucking her sister's breasts for 10 years. (Peach Family VOL.5, SDMF-003)

"This started when his younger sister had her first period." The older brother, a shut-in, sucked on his sister's G-cup breasts like a baby for 10 years. The various ways he did this give you a glimpse into the "abnormal daily life" of a certain family.