So what’s the 86 mean?

Someone like Ian, haha

And as shown in the flashback, Ian's phone had the date August 6 on it, which is basically the date he met Eunsan. So the 86 is most likely a reference to that day.

And a yearner is basically someone who is constantly longing for or pining after someone. In Ian's case~ he's the CEO, founder, and sole employee of the Eunsan Yearning Association. ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄