A mother who is at the highest level of frustration at a friend's house where she went to stay overnight

While my parents were traveling abroad, I ended up staying at Kosuke's house, who lives nearby. My mother had also told me to study hard, so I was purely planning on studying with Kosuke. Kosuke is also good at studying... However, when I went to Kosuke's house, my goal was instantly lost. I happened to encounter a scene where Kosuke's mother masturbates. I hurriedly looked away, but the situation started to roll in an unexpected direction...