Tomoki and his wife Nozomi have to move due to a job transfer.
Due to the sudden change, it was difficult to find a property.
At that time, his sister Ryoko and her husband, who lived near where he was transferred, offered to live with him until they found a property.

A welcome party was held on the first day of living together.
Nozomi is not good with alcohol and leaves the group early.
His sister's husband also went to the bedroom early for work the next day.

Tomoki was drinking while talking about old times with his sister, but his consciousness gradually faded and he eventually passed out.

And when he woke up, he saw his sister straddling Tomoki's waist right in front of him.

"I couldn't resist...it's been a while since I last saw you..."

[Edited from DLsite]