Middle-Aged Businessman, Arise in Another World! Volume 1 by Sai Sumimori

Onigawara Shouzou spends his days working a tiresome job at an IT company, but his life changes when, on a rainy night, he meets a goddess named Silvia—and that's not an exaggeration, she's an actual goddess! That night, she stays in Shouzou's apartment, and their growing attraction to one another becomes more apparent as the night goes on...