I've seen alot of NTRs but NEVER have i seen the cuck having to directly help undress their S.O. and the guy so that they can get to the nasty. This is levels of being in the chair i didn't think was possible...
This would be terrible if the sensei wasn't a scumbag. But since he is, there's no sympathy he deserves. After what he did to Kanae, this is just deserts.