This is a branch of the original Butagumi, which is a ten minute walk away from here on the other side of the motorway that cuts through this area. The Roppongi Hills complex is large and labyrinthine, quite possibly modelled on a three dimensional version of the maze of Knossos but minus the minotaur. The restaurant is located at the B1 basement level of the North tower, in a side corridor a few yards from the entrance to the subway. Allow plenty of time to find it.
There is a central open kitchen with counter seats arranged around this, so you can see the chefs at work. There was a little nibble of cold sweet potato with a mystery marinade, which was moderately unpleasant, but I was here for the tonkatsu. You can have sirloin or fillet in different sized portions, with a choice of several different pork varieties. I went for kurobata (black pig) from Kanagawa, perhaps the most prized pork in Japan. The breadcrumb coating was crisp but the pork, though it had good flavour, was a touch chewy in places, which was a shame. This was probably down to the individual piece of meat rather than any generic issue (12/20). The savoury sauce served with it was good, as was the traditional shredded cabbage. Miso soup curiously, was better than at the original Butagumi branch.
Service was efficient and the bill came to ¥2,820 (£18) a head, with a small beer to drink. If you want to try Butagumi then I suggest you stick to the original branch nearby, which has much more atmosphere, a broader choice of pork and was better based on my experience of trying the identical tonkatsu at both branches on the same day.