This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Katanagatari
Konayuki's visit to the graves of her fellow villagers, where she drops her cheerful fašade and tearfully admits that she's lonely, and only lied to Shichika and Togame so they would stay with her.
The scene at the end of episode 7 with Nanami and Shichika as children, eating watermelon under a tree, is highly tear inducing.
"Chou...Chou..." Combined with Dying Alone and a fleeting fantasy about reuniting with her dead fiance, Oshidori gets a rather sad send-off as she sacrifices her life to buy her comrades time escaping from Emonzaemon.
Pretty much the entire first quarter of episode 12 as Togame bleeds to death. Shichika's voice actor really carries the scene through.
Before the fight with Emonzaemon, when Shichika is remembering his time spent with Togame.
The closing narration sums it up with heart-wrenching clarity.
The ones who failed at revenge, the ones who failed at their goals, the ones who fell before achieving their aspirations, the ones who didn't succeed... Those who lost, those who stumbled, those who rotted... Those who fought with all their might, and sacrificed everything, only to have their work be for naught, yielding fruitless results... Who died unfairly, or perhaps illogically, tragically, without face, full of regrets... The story which offers a happy future for them, full of hopes and dreams, Katanagatari, quietly lowers its curtains here.