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Tear Jerker: Hunter X Hunter
The events of chapters 304-307 in Hunter × Hunter. Seeing the Kid Herobreak and give in to rage and despair is heartwrenching.
After Kurapika kills Uvogin, he falls to his knees and holds his head in horror. The next time we see him, he goes to his hotel room, and starts to chant the Kurata prayer slowly, traumatized. Poor guy.
The Chimera Ant King's death, especially with the pure black panels fitting his dying dialogue, which makes his death even sadder. It's almost a Japanese When the Wind Blows.