all u ppl hatin on this arent getting it, chakra isnt physical juss cause u have enough doesnt make it assured that it will work, kakashi explained that in like episode 6 in part 1, the life (yin) chakra is still in the fox but the yang isnt, you would need both halves to make the ten tails, if u only needed one then izanagi wouldnt be very strong in the sages hands it clearly says u need both sides to make something u need the yang to make a body n the yin to breed life into it, otherwise ul juss have a huge mass of chakra floating around with no vessel, s**t goes both ways u kno