He isnt innocent. However, he does very much put up a front of innocence. A front like he doesnt notice things when he most definitely does.
He feels more safe whenever EVERYONE thinks he is a solid, half dumb, block. Realistically he is more of a person than anyone could imagine. He didnt act like this untill his mother passed. The only people who have truly seen him act himself are his father, Senjuro, and Tengen.