[Seika Kairaku Shoten (Bairasu, koflif)] TS Succubus ~Ikidaore no Succubus o Tasuketara Nyotaika saseraremashita. Onnanoko no Karada tte Konnna ni Kimochi Ii no!?~
Man who works for a black company and hates his life finds a girl collapsed on the side of the road and takes her home to nurse her. Turns out she's a succubus who had collapsed from not "eating" and he proceeds to "feed" her. As a "reward" for helping her (as if the act itself wasn't reward enough) she turns him into a succubus. At first he rejects it, so she gives him a grace period and tells him if he still doesn't want to be a succubus after a few days she'll turn him back.
We all know how the rest goes. As if anyone would actually choose a life of soul-killing corporate slavery over doing whatever the fuck you want as a hot succubus.