This is an original JK story from Comiket 90!

Mana Sano is a high school girl who worked as a tutor. After a class, she couldn't go home due to a sudden storm. Her student's father invited her to stay until the rain stoped. After dinner, Mana was helping to wash dishes while chatting with the father, when his hand suddenly grabbed her from behind...

(Source: Booth, translated)