I've been here twice... both times indulging in the unadvertised happy hour of 4:30 - 6:30 M-F (ask for the Happy Hour menu!)
Beers/wine/cocktails are all half price. I was underwhelmed by the cocktail I had, but happened to love the Japanese beer - who knew?
I'm not a sushi queen by any mean... but their happy hour sushi was well priced ($5/roll of 4-6 pieces) - and I have enjoyed the rolls. Their happy hour menu includes miso soup & edamame... as well as spicy tuna roll, vegetable tempura roll, roll of the day, and something else that I know I've had - and can't remember. I LOVE the tempura roll! Definitely a great happy hour spot in Tremont!
Can I just take a minute to mention that the staff is fabulous? They were perfect in timing, kind - but not overbearing. Great with suggestions, and making us feel welcome.
Finally - the decor is completely unusual. The restaurant is subterranean, but the place still feels bright (thanks to the vivid use of color in a completely sophisticated tokyo style way). The restaurant is on the small side... but it's definitely a fun, unique little spot!