Arigatou

Arigatou (ありがとう) is a manga series by Naoki Yamamoto. It was serialized in Big Comic Spirits.

Plot
A depressing story about how a Japanese family's life goes wrong: an immoral protagonist, her sister who was gang raped before, her alcoholic mother who later devoted her life to a cult, and her father who lost favor with his company... full of sexual content and highly violent.