O-KATSU is a tonkatsu restaurant in the alley of Yeonmujang-gil in Seongsu, Seoul, serving hire katsu, loin katsu, and shrimp katsu. The hire katsu is tender and chews well, the fried coating stays crisp to the end, and the shrimp katsu is densely filled. Orders and payment are completed at the entrance before entering, and whether there is a wait has to be checked separately inside the store. Dishes different from what was ordered sometimes come out, so the order needs to be checked after entering.