Inmananoni, Tadanoningen ni An'an Nakasa re Chaimashita.

The ordinary office lady Eri has a secret. She is a succubus who feeds on men's sexual energy! But Eri was actually still a virgin due to her constant failures at seduction, until she caught the attention of Tatsumi, her senior at work, and they went to bed together. This was the first time she's ever been kissed so deeply, her nipples being teased, and her body caressed until her insides throbbed... She was so hungry that they made love over and over again until morning! The senpai was a better lover than a succubus!

(Source: Love Kyun, translated)