Okami-sama was included in a collection named Rohan Kishibe Does Not Shout with four other stories, which released for sale on June 19, 2018. Okami-sama is on pages 199-265 in the volume.
Rohan visits a tax office where his tax accountant, Seiko Sakanoue (坂ノ上 誠子, Sakanoue Seiko), preaches to him about how he should manage his money. His story of "I bought six mountains just for collecting data on the Yokai legend and went bankrupt" was particularly disturbing to her. While Rohan acts as if he's remorseful, Seiko finds a receipt with "Okami-sama" written in the address field. Rohan asks about it, and Seiko reveals that if you write "Okami-sama" as the recipient of a receipt, the fact that you would have to pay for it disappears. However, Rohan couldn't hear the whole story as Seiko received a call from another guest.
Interested in the effects, Rohan tries out writing "Okami-sama" on his way back from the fan event that he appeared in.