This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Garo The One Who Shines In The Darkness
Episode 7: Poor Rui who is the only survivor her family after the rest of them were devoured by the horrors. They came to Vol City in hope to start a new better life but were lured into a trap by horrors. While they were able to escape the first time thanks to the Ryuga and the others, they weren't so lucky the second time after Sonshi brainwashed them to go back with only Rui escaping thanks to a memento from Takeru snapping her out of the brainwashing, barely escaping with her life. Rui whole entire memory was erased without any memory of her family and believed that she is a orphan without any family to most likely spare of her the pain but in the end is that the really best for her?
Episode 9: after Ryuga is framed for murder, we see him running through the city, every persone who interactid with him now terrified.
Episode 13: The scene where it shows all the people whose bodies were destroyed and their souls stored into capsules to act as a food source for horrors. All those people who came to Vol City to look for a better life was cruelly taken from them to become food for Horrors. Rui's family was also shown and Takeru's reaction was heartbreaking. The crew managed to give these souls peace but in the end it is sad to know that most of these people were innocent and had dreams that were taken away from them by the Horrors
Episode 17: Everyone's reactions when they find out they were too late and Touse has killed every other Kaneshiro in the city. And then the murderes are pegged on them. Ryuga can only scream.
Episode 21: Enhou finally died as herself and in the eyes of her subordinates, as a true hero.
Also, the bar scene, with the shared camaraderie between the Makai Knights and SG-1's troopers, and Enhou's children with her boyfriend happily greeting her. It's really heartbreaking, because it shows what could have been had Enhou not been turned into a Madou Horror.
Episode 23: Right after Ryuga had defeated Sonshi and managed to restore the armor of GARO to its golden brilliance, he was forced to kill his own mother due to And Then Hakana Was A Horror, which was caused by her being forced to give birth to multiple Madou Horror Plants. What really twists the knife is the fact that she didn't even get to see its golden glow due to having let herself be blinded to restore Ryuga's eyesight.