OK firstly, the "rule" is no boys (tee hee) We're not sure of the origins, he's not gay and it's certainly not a host bar but boys just aren't allowed. Except for the owner's closest male friends of course which consists of 10 blokes, almost enough to fill the entire bar!
Secondly back to the cocktails. Seriously some of the best I've tasted (although I'm not the cocktail expert) My fave is a vodka based cocktail with a Yuzu (Japanese citrus fruit) jam at the bottom so you end up sucking the yuzu through your straw. Delicious refresher after a big meal I say!
If you're walking past Kohrinbo 109 on the right towards the turquoise Katamatchi bridge, hook an immediate right straight after Kohrinbo. Heartbreak Bar is located just on the corner. Exact location is here
You'll see these posters outside (that owner designed himself- hes a former graphic artist....) and you'll need to go up one flight of stairs.