[Umino Yayoi] Kashintan | Flower Core Tale (Yami no Kenzoku)

Mimiko becomes entangled in a hazy family fantasy involving her brother, an imposing older sister, and their mother’s worried questions about sleep, dreams, and a changing body. The buxom sister’s enormous bosom and teasing dominance drive a chain of intimate encounters, erotic sleepwalking, and whispered instructions, while the brother’s embarrassment sharpens the taboo tension. A final schoolyard exchange turns those revelations into promises of further transformation, leaving the household suspended between secrecy, success, and escalating unease.