Board Thread:Theories and Speculation/@comment-32742265-20180101204845/@comment-25122992-20180101205722

Hashi's regeneration is not the only one exclusive ability that provides a faster wounds' regeneration rate. We've seen several alternatives as well, among them, Uzumaki healing ability (which Kabuto demonstrated) and so called Power of the White Snake. So, it's impossible to say which one is the ability Mitsuki used or if it's even some new ability that never appeared before.