In the anime series "Hunter x Hunter," Menthuthuyoupi, also known as Youpi, does not die in battle or from an attack by a protagonist. Unlike some of the other characters in the series, Youpi experiences a more peaceful end.
Youpi's death is a result of the shared life energy process of the Chimera Ant King, Meruem. After the extremely powerful battle with Netero, Meruem is left severely weakened and poisoned due to a nuclear bomb known as "Miniature Rose." In an attempt to heal and revitalize Meruem, two of his Royal Guards, Shaiapouf and Menthuthuyoupi, offered their own bodies and life energy to him. This process drained their life force, leading to Youpi's death.
The important point here is that Youpi didn't die from any battle wounds or from losing any fight, but from willingly giving up his life for his King, Meruem.
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