Naruto Debuts Boruto's New Berserk Form Rasengan: Watch
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Episode 208 of the series picks up right after an unconscious Boruto suddenly awakens with a fully activated Karma seal. Giving him a Byakugan eye, this new form also gave Boruto a huge boost in power that easily took down Boro's monstrous form. Not only that, but it was revealed that this gave him a much deeper connection with the Momoshiki Otsutsuki residing within him and it led Sarada and the others to figure out that there's something far more dangerous about Kawaki than they realize.
So while Boruto and Kawaki had been able to use Karma for good and to boost their attacks to new levels, it appears that the continuous use of that power has granted another being even more control of Boruto's body. This short demonstration of Boruto's power with the full use of his Karma and Rasengan jutsu, only teases what a full takeover in this berserk new form could lead to. Thankfully, using this Rasengan drained the form of its power and cut it off quickly.