I walked by Koyoi a few months ago and looked like a lot of jap ppl in there. Made a mental note and checked it out. It didn't disappoint me, very authentic jap izakaya. I like it better than Guu/Don Don. So far I tried quite a few things on their menu: Beef tataki, okonomiyaki, Koyoi salad were my favs.
Of coz, to complete a meal, we gotta have desserts: Greentea rare cheesecake is a must try and their black sesame ice-cream was good too.
It's definitely a hidden gem.