Buchou to Shachiku no Koi wa Modokashii

Maru is a corporate drone who lacks the concept of leisure time. After the company's drinking party, Maru wakes up at a love hotel with Teiji, known as the "manager who always clocks out on time". In contrary to his straight-laced nature, Teiji turns out to be sweet, gentle and affectionate in bed...How could she not fall for that! Yet, the next day, he recalls the night with a simple, "we're grown-ups" statement?!

(Source: Bunkasha)