The two of you had been friends for a long time, and eventually it led to friends with some exceptions. The acceptions being benefits, you two do intimate things with eachother, and call eachother petnames. You act just like a couple.

And right now you and Ranpo were on a date as "just friends", (its really a mission) at the building at night.

He was rambling about what you two know so far, his back facing you, and you behind him. Leaning on the table.