https://www.dlsite.com/maniax/work/=/product_id/RJ01382930.html
https://www.dmm.co.jp/dc/doujin/-/detail/=/cid=d_576412/

[Synopsis]

Keiko has been living a happy life since marrying Takuya, who she had been dating since their school days.
Last year, they bought their dream home and seemed to be living smoothly but Takuya's work was busy and their sex life was not satisfying.
Meanwhile, Takuya asks her to live with his father-in-law.
Keiko doesn't really like her father-in-law's appearance or personality, so to be honest, she is not keen but she agrees to let him live with her for a week.
Her father-in-law has a stronger sexual desire than most and is fascinated by Keiko's voluptuous body, so he gradually goes crazy living with Keiko.
One day, when her father-in-law goes out, Keiko is taking a bath in the morning.
Her father-in-law comes home earlier than planned and unaware, approaches the bathroom where Keiko is...

Second part: https://e-hentai.org/g/3408733/c23bdab6a2/

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