It revolves around a student named Rio Sakaki, who is suicidally depressed. Her father is distant, and her stepmother is emotionally abusive. She can't remember her early childhood when her sister and biological mother left. Her therapists, Doctors Shoumitsu and Kyouko Minori do their best to help her situation. Everything changes when Rio meets classmate Sahoko Higa, and they fall in love. With Sahoko's support, it seems like everything in Rio's life is changing for the better...
Pieta contains examples of:
- Abusive Parents: Rio's stepmother Shigeko is cruelly dismissive and seems to be fixated on destroying Rio emotionally, and her father is almost completely apathetic to her.
- Bifauxnen: Rio. She's mistaken for a guy at least once within the story.
- Break the Cutie: Shigeko deliberately tries to crush Rio's spirit whenever she can, and finally manipulates Rio into attempting suicide by playing on her missing memories of her sister and insinuating that Rio actually killed her, which is not even remotely true (even Rio's father admits this when Shoumitsu confronts them about it).
- Distant Finale
- Driven to Suicide: Rio attempted suicide often, but was starting to improve thanks to Sahoko. Then Shigeko lied to her about her sister's death, which caused her to jump off the roof of a building. She lived, though
- Freak Out: Shigeko has one when she catches her house on fire by burning Rio's photo album; when the Minoris are discussing it in the next chapter, Shoumitsu mentions that she hasn't completely recovered from the emotional shock.
- I Did What I Had to Do: Shigeko's rant to Shoumitsu about manipulating Rio into her final suicide attempt reeks of this.
- Girls Love Stuffed Animals: Rio has a teddy bear that she's kept most of her life.
- Hikikomori: Sahoko is a recovering hikikomori.
- Hoist By Her Own Petard: When burning photos of your step-daughter, do it in a place where it won't light up the rest of the house.
- It Always Rains at Funerals: When Rio jumps off the school building.
- Laser-Guided Karma: Shigeko burns Rio's photo album, and sets her new castle on fire.
- Mama Bear: Shigeko sees herself as this; she's determined to make a happy home for herself and her biological child and sees Rio as a dangerous impediment to her happiness.
- Pietà Plagiarism: Not all that surprising, considering the name of the series, it happens when Sahoko is cradling Rio's broken body after she jumps off the school building.
- The Scapegoat: Shigeko believes that Rio tried to kill her son when he was a toddler. What really happened is that Rio had cut her wrists, and the boy wandered into the room, slipped in the blood, and fell, hitting his head. Shigeko heard his cries, came into the room, and jumped to the entirely wrong conclusion.
