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Munchy: Then why is "Suicide" considered illegal and punishable by law in many countries? Isn't
Suicide a person's own simple wish to die; why make it illegal or try to stop with therapy?
Here, its clear that the Elves not having any desire is a mental disorder, which they suffer because of their long life-span and their act of not eating which could end up causing them to die is in a way an act of
Suicide. And considering that those three are the last of their kind (atleast the previous chapter did mention it, if the translation was right), it isn't odd for them to be forced to live.
Also, the choice wasn't MC's, it was the
middle Elf sister who asked MC to save her two sisters.