Ikeda Etsuko

The continuation of Deimos no Hanayome (which was unfinished) but with new character designs and updated artwork. Deimos was once a handsome god. He loved a beautiful goddess who returns his sentiments. The problem, well, she is his sister. For their crime against nature they were struck down out of Olympus. The brother is now a demon and the sister a rotting corpse at the bottom of the ocean. Deimos must choose between his sister and her living human incarnation. His sister is jealous. The girl is horrified and unsure of just what to make of her situation. (from mangaupdates)

A wedding ruined by the suicide of a woman rumored to be a witch… Eiichi's affair ends in disaster as his lover hangs herself during his wedding to another woman. To the horror of the wedding guests, the dead woman gives birth to a girl. Eiichi and his new wife are forced to raise a child they don't want and don't care for. They name her Tsumiko (Great Shame). Now as a teenager Tsumiko resembles her dead mother more every day. She must compete with a younger sister, Megumi, who is everything she is not. As tensions rise at home and at school, Tsumiko will do everything she can to make her life better…

Ayako is a young girl of wealthy family, but in her past hides a terrible secret: her real mother had been raped in prison by a mysterious hideous creature, resulting in her birth. Ayako is perpetually chased by Dr. Ogata, who is trying to expose her demonic origins. The work remained incomplete, consisting of six independent chapters.

(from ebookjapan): The betrayal of the man she loves awakens the mark of the devil - the Λ (lambda) birthmark! Mari, who has a "Λ" birthmark on her arm, works as a servant at the Kaibara Zaibatsu's mansion and is sent to school. Her boyfriend Kaji, a lawyer who frequents the mansion, is her emotional support. One day, Kaji brings Ayako, the niece of General Kaibara, who has been missing. When Ayako shows up, Mari's happy days are over... An innocent soul, exposed to betrayal and lust in the glamorous world of society, is transformed into a demon! The cruel, pathetic, and brilliant mystery of Mari, who became the avenging godchild! Note: Was serialized as two parts: Part 1 in Jotomo, 1977, Part 2 in Petit Seven, 1979.

Deimos was once a handsome god. He loved a beautiful goddess who returns his sentiments. The only problem was that she is his sister. For their crime against nature they were struck down out of Olympus. The brother is now a demon and the sister a rotting corpse at the bottom of the ocean. Deimos now has to choose between his sister and her living human incarnation but the sister is jealous, while the girl is horrified and unsure of just what to make of her situation.

During the end of the Bakumatsu era there is a young woman by the name of Hisa, haunted by the accursed birthmark in the shape of a crimson red butterfly that appears on her body in times of great duress. How far will Hisa go to seek justice for her unfortunate life, and the man that she loves?