Unrestrained Sex with a Childhood Friend Who's a Self-Proclaimed Slut (Lie)

The protagonist got invited to have sex by his childhood friend who calls herself a slut, and without knowing whether it was true or not, he thoroughly enjoyed trying out a rough sex play on her.

"By the time he realized that she was lying about being a slut, she was a total mess..." it's that kind of story.
Despite that, the ending is depicted in a legitimately lovey-dovey way.

(Source: Melonbooks, translated)

Released at Comiket 97.