Hyungboo means "brother-in-law" in Korean and I don't know whose brother-in-law this restaurant refers to, but it serves up the best, most authentic Korean food I've had in Tokyo. Mainly, this means that they don't add sugar to their jjigaes (stews) and soups.
Note #1 to other Korean restaurants in Tokyo: unlike Japanese food, Korean food is not supposed to be sweet. Please do not add sugar to soups and stews, it ruins them.
Note #2 to other Korean restaurants in Tokyo: please do not charge for kimchi. Hyungboo offers gutjuri (fresh, unfermented version of kimchi) for FREE and it is lip-smackingly delicious, totally worth the smell of garlic that will reek from all your pores all day.
Like most restaurants in Tokyo, lunch offers the best deal with an entire page of options that include rice, banchan (side dishes) and soup or meat (or both) for 1200 yen or less. Their lunch Special "D," which comes with spicy sauteed chicken on top of rice, soondubu (spicy soft tofu stew) and banchan was especially good, as was their yukgaejang (spicy beef soup - not on the lunch menu but can be ordered off the regular menu).
Seafood and cheese pancake - a bit greasy but we had to try it as I've never seen attempts at Korean-Italian fusion before
Spicy chicken on rice
Food rating: ****
Bang for buck rating: 4
Location: on a side street about 3 minute walk from Akasaka Sacas
Average price of meal for two (lunch): 2500 yen (~$28)