Cry Out.

Akiko, a girl living a hard life after her father passes away and her mother's new boyfriend turns abusive, starts receiving encouraging letters from her 30-year-old-future self. Akiko also starts to get bullied in school, and her teacher Shinomiya tries to help her, but ends up losing her job. Akiko also unearths a story written to her by her father, telling her how he originally met her mother, who was the abused daughter of a politician.