Tsuma ni Damatte Sokubaikai ni Ikun ja Nakatta

Yumiko’s husband always goes on business trips during the Obon and year-end holidays. When Yumiko was feeling lonely and having a hard time with her sexual desire, she found a hentai doujinshi in her husband’s room during his business trip. Her husband, who she thought didn’t have a strong sex drive, has this book… While Yumiko is masturbating and imagining intense sex with her husband like in the doujinshi, a young man who lives in the neighborhood comes up to her and…? Unable to resist the young man’s intense sex, Yumiko is drowned in her own lust…!

(Source: Lune-soft, translated)