We usually think of cafes being located on street level with a pretty signboard and interesting decor to invite you in but the crazy rents in Hong Kong have caused many cafes to move up higher within the multitudes of commercial buildings that dot the Hong Kong landscape. Most of them have nary a signboard or facade to warn you that they are there though!
Fullcup Cafe is located on the 3-7F of a building in Mongkok, and was recommended to us by our friends of friends to go to for live music. I had also found it independently so the extra recommendations made this an immediate must-go for us. Sadly, our dates were wrong for a live music event. Next time.
We got really lost trying to figure out how to actually get into the building. There's no public lobby that opens out from the main road, rather we had to walk down a dingy alley to find this orange sign and then futilely try to push open some likely-looking doors until a security guard took pity on us and showed us where the elevators were.
When we got there, the main floor of the cafe was full with locals and we got moved up to an empty 5th (or was it 6th) floor. This floor had a retro-grunge bar kind of feeling. We took a window seat, and it was fun to observe the hustle & bustle of Hong Kong from high up. Through it all, no one else came up to join us.