still can't kenjaku actually look like - what am i missing?

Noritoshi Kamo is another one worth knowing, the guy behind the death paintings. That was Kenjaku too, in an earlier body. So when people say it 'looks like' Geto they really mean Geto is just the current outfit.

the confusing part is that kenjaku doesn't really have a look of its own. it's a brain that moves into other people's bodies, so for most of the story you're seeing geto's body with the stitches across the forehead. that stitch line is where the skull opens. when it does you see the real thing, a brain with a mouth on it. it wore other bodies before geto too, yuji's mum being the big reveal, and she has the same scar.