I visited Sushi Kyomei between Magok Station and Balsan Station in Gangseo-gu. It was a cheap sushi omakase for 80,000 won for dinner, but
it was run by one person, so the food course progressed a bit slowly.
The food itself was as delicious as a high-end sushi restaurant.
I recommend it if you are near Gangseo-gu.