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He hardly showed any emotions outside of anger when prisoners tried to defy him for example and was not hesitant in punishing them in the most cruel of ways. He took his duties very seriously and followed the rules to the letter. As a result, he sought a way to reopen the box to ask for his son back, unbeknownst to his superiors. However, Muku didn't have enough chakra and was sucked into the box instead, leaving Mui grief-stricken. Ten years ago, as the guardian of the Box of Ultimate Bliss, Mui, tried opening it once with Muku's chakra, in the hopes of asking the box to grant them the wish of reviving Kusagakure to its former glory.
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He was a caring father who loved his son deeply, often taking Muku to eat ramen. Mui's wife passed away not long after their son, Muku, was born, so he raised him all by himself.
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