Kakawatte wa Ikenai Type no Musume ga Kanojo ni Natta

The female protagonist, Miyu, is your typical gold-digger girl—she hooks up with guys, milks them for all they're worth, then dumps them and moves on to her next prey. Yuuki-kun, her latest target, seems to just be your typical nice guy that genuinely looks out for Miyu, completely oblivious of her intentions. However, something's different about him that makes Miyu unable to carry on her usual scheme...

(Source: MangaDex)