Guai GUI is a restaurant on the second floor of the Isaac Toast building, a five-minute walk from Saetgang Station in Yeouido, Seoul. It serves a beef yakiniku course in which diners grill cuts such as sirloin and boneless short ribs themselves over a small Japanese-style brazier, and the course also includes grilled cheese and grilled hairtail. Nagasaki champon is served with added Japanese-style fresh noodles, and the lunch course is divided into A, B, and C. Visiting in the evening without a reservation is difficult.