Board Thread:Boruto Discussions/@comment-3523655-20171013043852/@comment-732150-20171013051815

Manga never said he was the one who made Kirigakure into the Bloody Mist. Or more accurately, they never said when it started precisely. We know only it ended with him. Bloody Mist was already a thing before Yagura became a jinchuriki (Kiri-nin called it Bloody Mist when Rin was made Isobu's jinchuriki), and since jinchuriki were traditionally made out of young children, he was probably a child, way before becoming a Kage. We don't know the extent of Obito's manipulation, neither in duration, nor in manner in which he was manipulated. For all we know, he just exacerbated what Yagura was already, and steered him to certain practices. No, he's not a kid, he mentions he is an adult when Naruto meets him, so he was already of legal age when he died. There is no mention of Shizuma being Kisame's child, they're just from the same clan. B probably returned Samehada at some point, and since relatives have similar chakra, Kisame being able to use it means Shizuma's chakra must be of similar quality or quantity. All your issues with this plot are due to wrong assumptions that can be cleared by reading relevant articles.