Jishou Bitch (Uso) no Osananajimi ni Tekagen Nashi Ecchi

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.