Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Tear Jerker: Ragnarok The Animation
Ragnarok: the Animation has one such moment when the Alice Maya is a friend of is forced to become a monster and Maya-chan kills her with her own hands before realizing who she is. The subsequent episode was a Tear Jerking episode after Maya realizes what she's done and apologizes to the already dead Alice.