Elfen Lied/Heartwarming

Early on, when Kouta realizes that Nyu endured the cold damp surf to try and get him a sea shell to replace the one she broke.
Later on after hearing Kouta talk about his last moments when his little sister Kanae and seeing his sad face. Nyu cuts her hair and impersonates Kanae saying she forgives him in order to console him.
Mayu has several as her backstory is revealed. One, when she reaches the beach and feels safe from her parents. Two, when she first meets Wanta. Three, when the bakery merchant gives Kouta and Yuka a birthday cake for her, and shortly after this, Wanta, having ditched his supposed true owner, comes scratching at the door of Maple House, having faithfully followed Mayu to their new home.
Nana, each time she tries a new food or realizes that she has a home at Maple House. Also when she sticks by Kurama during his bout with mental illness, when he tells her she was nothing but an experimental subject to him.
Kurama, when his love for his adoptive daughter Nana is so fierce, he kills Barbara, a vicious clone of his real daughter Mariko, to protect Nana.
Nozomi, when she accepts the encouragement of Kouta and Yuka to keep on singing, and later, when she asserts herself to her worried and misguidedly overprotective father.
Yuka, when she flees to the beach, believing Kouta loves Nyu more, only to have Kouta come to retrieve her, angry that she should worry him, and proving he loves her by his concern.
Lucy, when she sings while healing the mortally wounded Kouta, knowing that doing so will cause her body to melt--and this is after he said he hated her for what she did to his family.
Kouta, in the very last panel of the manga, as he smiles and sees that his daughter's playmates are somehow connected with Lucy and Nyu, possibly their reincarnations.
The very last reunion between Kouta and Lucy, it's both a Tear Jerker and a Crowning Moment of Heartwarming in both versions.
- Manga: Kouta may be hateful and bitter about what Lucy did, but he's still willing to let her stay with them, on the condition to never kill again, and then he embraces her when she accepts, even Taking the Bullet Kur ama shot at her.
- Anime: Kouta is still unforgiving, but ends up openly admiting that he loves her, then a tearful Lucy kisses him before leaving.
Mayu finding out that Bando is still alive in the last chapter despite being cut in half by Lucy the last time she saw him. Considering this is a series where Anyone Can Die even the protagonist, it was a relief to see a previously thought dead character turn out alive and well.
The ending to the chapter that explains Nozomi's backstory We see the cassette tape that her father broke earlier taped back together in a drawer
- And the end. More precisely, one of the endings of the anime or the manga, depending on which ending you felt to be the happy one.