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Tear Jerker: Prétear
Mawata's breakdown in Prétear. Specially when Sasame, whom she loved, ends up abandoning her for Takako. In front of her family. After Mawata snapped on them. And then Takako steals Mawata's heart and makes her a Barrier Maiden by locking her in the Tree of Fenrir...
To make things worse, right before that we had Natsue's flashback to her first husband's death. Where Mawata was Wise Beyond Her Years and was the one comforting Natsue and Mayune. How... ironic, to say at least. And coupled with the aforementioned scene, a BIG ASS tear jerker.
In the second-last episode, we get Mayune, Natsue, Kaoru, and Himeno going to save her from the Tree. We're shown clip after clip of them pulling on the vines surrounding her, calling her name. Even when Takako physically attacks them with lightning, and they've been pulling on regenerating vines for a long time, they still don't give up. And when you consider Mayune and Kaoru were comic relief characters it deals an even bigger blow.
The final episode. Himeno and Hayate merge to battle the Tree of Fenrir and rescue Takako. Hayate repeatedly takes blows for Himeno until ultimately she is pinned down and unable to move, begging him to stop shielding her; he refuses to stop, and ends up sacrificing himself to protect her, using the last of his strength to cut her free before he collapses, then telling her to escape.
Before that, there's also the scene where Sasame is dying after protecting Takako. "Am I finally able to be your knight?" And then he actually dies, and Takako starts repeatedly calling out for him in despair. The particular piece of BGM that plays during that last moment makes things even worse. Let's just say most of the final episode is a Tear Jerker, until the True Love's Kiss.
Especially the True Love's Kiss scene, with everyone, and I mean everyone crying over Himeko's dead body. Even Mayune is sobbing, demanding to know why Himeko had to die, why she did what she did, and Hayate's line before he kisses her."Please, let me see that smile again..."