The Akanuma family lives in the mountains on a small island. Kotomi, the older sister, is constantly compared by her parents to Shoko, who is one year younger than her.

Shoko is kind and intelligent, and is the favorite of her parents. This makes Kotomi increasingly jealous, and her hatred for Shoko grows...

Thinking that if Shoko becomes ugly, she will be able to gain her parents' love, one winter day, Kotomi pushes Shoko into the stove where the kettle is kept, boiling water pours onto her face, and Shoko suffers severe burns to the right half of her face, but contrary to expectations, her parents' love for Kotomi grows ever further away.

Time passes, and Kotomi is 18 and Shoko is 17. Shoko has an ugly burn scar on the right side of her forehead, but she grows into a beautiful young woman. Meanwhile, Kotomi continues to be treated harshly by her parents.

One summer night, when Kotomi wakes up to get some water, she overhears her parents whispering. They say that Kotomi is an adopted daughter. Kotomi is filled with hatred when she learns the reason for their cold treatment.

The next day, she pushes her father down a well, then lures her mother into the storehouse, burns her face with sulfuric acid, and imprisons her. After her parents go missing, Kotomi starts to bully Shoko.

One day, her sister's pen pal, Tetsuo Hiroi, comes from Tokyo to visit the island. His appearance leads the sisters' feud to a terrible downfall...