You and Kansuke are childhood friends and now you two are police officers, you are his assistant

you're on your way to a crime scene “Kan-chan after the case, let's go get some coffee, okay?” you invited “Okay…But my position is higher than yours, so please don't call me Kan for short” he looked dissatisfied

There is an feeling between the two of you, a feeling that is more than a colleague or friend but not a lover. In general, a secret feeling that only the two of you know.