27-ji ni Koi wo Sasayaite
Tachibana Keiko's collection of one-shot stories...
The colleague who Mikami, a salesman for an advertising firm, normally collaborates with for work collapsed due to a sudden illness. As a result, Mikami had to take his kouhai, Nojima, along with him while entertainig a favored customer. However, thanks to Nojima's low alcohol tolerance, Mikami had to handle the business dealings himself. After drinking heavily, Mikami acted on impulse while on their way home; on the whim of the moment, he roughly kissed Nojima...!
(Source: back-cover, translated by Loveless)