Work long enough and hard enough at a job, and you will succumb to the stress.  On top of the stress of the job, our protagonist has been asked to work at the Head Office - falling deeper into depression.  It is only a brochure he picks up as he returns to his hotel telling him of an online delivery service that "one can simply not miss" that lifts his mood.  Once you seek the entertainment and pleasure of these delivery boys, their cute charm makes you unable to resist.  
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(Source: Nekopoi and Has Been Translated and Edited)