SILK-2012 Tonight, in the same bed. - Kanna Misaki

Nomura, a highly competent and respected employee, secretly harbors a problem: she's a second virgin with a low "romance quotient." One day, after making a huge mistake—something she never usually does—she's working overtime alone and bursting into tears. Coincidentally, her junior colleague, Nakamori, appears and offers to help her despite the late hour. From that day on, their relationship rapidly develops, but Nomura, inexperienced with the opposite sex, starts avoiding Nakamori...!