https://www.dlsite.com/girls/work/=/product_id/RJ01030314.html
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Senior, I don't know such a thing - His fingers that were accompaniment are now disturbing my vagina -

When I was in junior high school, I was confessed to a senior who was one step older. A person who plays the piano and has beautiful thin and long fingertips. Still, his face and grades were by far the best in the rural school, so he was a very conspicuous person.
Even after we started dating, I was afraid of getting frustrated and hurt, so I ended up saying goodbye to myself and breaking up with him right away. The truth is, I really liked it. That feeling eventually became like an obsession... Even now, as an adult, I can't stop secretly peeking at my seniors' SNS.
One day, I found a mark on a post I posted on social media. From the DM I sent with courage, I decided to meet my senior for the first time in 5 years. He is still the same as he was back then, and he is a cool senior. But I'm not the pure girl I was back then.
"I really liked my senior, and the reason I broke up with him was because I liked him too much..."
"Hmm. Then you don't like it anymore?"
- Her lips are taken away by her seniors and she is stared at. 「... How can I do any more and not like it?"
The beautiful and long fingers of my senior, who I admired at that time, playing the piano, were tracing my body on the bed tonight.

Got this translation from here: https://comiko.net/series/155586

Someone in another thread said this "For people who think the story is 'suck' or 'depressing', the story actually a real life event. It's from a forum called THE Waidan, where people will share their personal story (in which usually have sex as part of it) and then some will be turned into a hentai manga. So there's that, your daily dose of depression. Anytime finding one page full of THE Waidan logo, or seeing a page with written short story (like the very last page in this manga) then the story is real, so don't come at the artist cause that's not them the one who wrote it. Peace."

Base +7