Dongjak lunch restaurant with crispy tonkatsu: Kosi Isu Branch

I found Kosi Isu Branch while searching for a good weekend lunch spot! I heard it is known for bukkake udon and tonkatsu, and that there is usually a wait!! So excited.

Kosi Isu Branch basics

• Hours: 11:20–21:00
• Break time: 15:20–17:00
• Location: 1-minute walk from Exit 9 of Isu Station
• Parking: 1 hour free in the underground parking lot

The one hour of free parking is so nice, although it might be a little short if the wait is long.

What are the wait and interior like?

When you arrive, there is a spot inside the restaurant to write your name on the waiting list like this! It is not a digital registration system—you put your name down and need to stay in front of the restaurant. It was a bit hot that day, so waiting out front was slightly tough. I waited in the shade to the side, haha.

There were quite a few tables inside, plus around four bar seats for solo diners, so I saw lots of people eating alone. There are high chairs, too! There is nothing specifically for babies to eat, but I think it is nice that it is a space you can visit together.

I took a photo because there was information on the one-hour parking support, Wi-Fi, and restroom passcode, haha. Since this is a restaurant with a wait, one hour may not be enough, but still, better than nothing, haha.

The menu, from cold udon to tonkatsu

Kosi Isu Branch basically has cold udon, hot udon, tonkatsu, donburi (rice bowls), kama udon, and sides. It seems the Naver menu does not include everything sold in the restaurant, so I photographed the tablet menu. Check the photos below to see what is available.

This is their signature bukkake udon!! It is cold udon.

They also have hot udon.

There are gyudon, karaage-don, and katsu-don, too. Each dish also comes in a spicy version!!

They also have warm bukkake udon, so if cold udon is unfamiliar to you, this could be a good choice.

For sides, there are fried shrimp, fried chicken, inari sushi, and more. They also have 300 ml beers, which seem easy to enjoy without going overboard. You can add extra soba sauce or bukkake sauce if you need it! ₩1,000 each!!

The homemade noodle tempura bukkake udon and tonkatsu I ordered

• Homemade noodle tempura bukkake udon: ₩11,000
• Fresh pork loin tonkatsu: ₩11,500
• Maze udon: ₩11,000

First up was the fresh pork loin tonkatsu! The color of the breading looked so crisp and delicious.

The tonkatsu comes with tonkatsu sauce, kkakdugi (cubed radish kimchi), danmuji (pickled yellow radish), clear soup, and wasabi.

I usually eat tonkatsu with fat marbling and a rosy-pink center, so having one cooked through and crisp for the first time in a while felt different, haha.

This is not low-temperature katsu—the breading is genuinely crunchy, and the meat is clean-tasting. I love a crust crunchy enough to scrape the roof of my mouth, so it was so delicious to have it again after a while! Haha.

Next came the homemade noodle tempura bukkake udon! It has one piece each of fried shrimp and kabocha squash, plus one inari sushi.

Don't the noodles look springy just from looking at them? You pour in the cold broth and eat it with just a little broth in the bowl!

Pour in the broth like this and give it a good mix—it is refreshing, almost like an udon version of buckwheat soba, and perfect for summer. The noodles themselves are really chewy and bouncy, too!

This is maze soba udon! I like maze soba, so I was curious because it came as udon and ordered it! If you like savory, salty maze soba, this would be a fine choice instead of another udon dish.

My overall take after waiting at 1 p.m. on Sunday

There was quite a wait at Kosi Isu Branch even at 1 p.m. on Sunday! After eating there, I understood why it is popular. The prices are not high and the food is good, making for a satisfying meal, haha. I want to come back whenever I get a craving for cold udon.