Really? I did not cry when Mogamett died he was wicked man.
You might not have liked him personally, but it's clear the author's intent was for him to be redeemed. Or at the very least, for his motives to be sympathetic. His backstory was honestly one of the most tragic in the series.
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My List
-Graveyard of the Fireflies: Whole Movie
-Penguindrum: The lamb analogy/story
-Rave Master: Reina, Hardner's Revelation
-Bleach: Five Lifetimes Confession
-Fairy Tail: Pretty much any Character death kills me
-Magi: Mogamett's Backstory, Alma Torran Massacre (that poor child x.x)
-One Piece: Usopp Leaving, Merry's Death (that ship had more development than Naru/Hina ;_;)
Probably some more I'm missing. The events only really make sense if you followed the series, but I'm too lazy to go into detail.