Devil is a Part-Timer Novel 05

The Devil is a Part-Timer Novel 5 is written by Satoshi Wagahara.

With the repairs to his dingy one-bedroom apartment completed, Maou needs a new TV, so...the Devil's going digital! The trouble is, Maou and Ashiya don't know the first thing about flat-screens, so they bring Emi's friend Rika along with them to the local big-box electronics outlet. For some reason, Suzuno ends up coming along, and it turns into a shopping tour with the whole gang!