Board Thread:Theories and Speculation/@comment-45444155-20200806213256/@comment-6769189-20200816073428

I believe you mean Mitsuki. The wiki does a bad job of actually explaining his Senjutsu, but he has Sage Mode and Sage Transformation. His initial form with the horn and the big color spot that covers both his eyes is Sage Transformation. In the anime he has displayed Sage Mode, with the only physical change being pigmentation around each of his eyes