Once my daughter walked in on her dad and I having sex-I was so freaked. I couldn't say we were snuggling bc I left her dad when she was w baby. We just still slept together occasionally. He had forgotten to lock the bathroom door so she came in through he bathroom and yelled "get off of her"!! I think I told her we were wrestling and bc we were under the covers and I had a long nightgown on I just pulled it down real quick and rushed her out of the room so her dad could put his pants back on. I was so worried she'd be upset but she totally forgot about it. It was a long time before I let him touch me again and I made sure all the doors were locked.
Literally, the time Naoi walked in, I've had my hand held to my mouth because what if Rin were to be awake through all that?! Such trauma that kid would have.
But still... poor sensei Σ(  ̄□ ̄||)