it rly depends how the laws in japan works towards movies I guess...? In america used to happen in the past, so I wouldnt exclude completly the possibility honestly (since its a kiss + a half naked but with lingerie)
shit he's already letting his wife put her into the business in the first place, that's just the next step, besides off-camera sexual favors to get roles
and it's not any better if he lets her do it at age 18