Dongjak udon restaurant with mochi-chewy house-made noodles: Kosi
In short
Kosi Isu Branch is a house-made noodle udon and tonkatsu restaurant in Dongjak, Seoul, on the first floor of the building in front of Isu Station Exit 9. On a first visit at 1pm on a Saturday, the tenbukkake udon cost 11,000 won and the half-and-half tonkatsu 13,500 won, and the chewy, rice-cake-like noodles made it the best cold udon eaten here in years. At Kosi Isu Branch, the bukkake udon comes before the tonkatsu.
Good to know
- Location
- 1F, Units 126 and 127, 300 Sadang-ro, Dongjak-gu, Seoul (1 minute from Isu Station Exit 9)
- Hours
- Daily 11:20–21:00
- Break time
- 15:20–17:00
- Parking
- 1 hour free in the building's underground parking lot
- Tenbukkake udon
- 11,000 won
- Half-and-half tonkatsu
- 13,500 won
- Seating
- Window seats for solo diners, tables for two, tables for four
as written by the visitor on Sep 6, 2026
Every time I passed by Isu Station, there was always a long waiting line at this tonkatsu-udon place, Kosi Isu Branch. I was so curious that I finally went, and it turned out to be the best cold udon I've had in recent years.
Udon made with self-made noodles. Spoiler alert: at Kosi Isu Branch, you have to get the bukkake udon. Seaweed flakes, chopped scallions, tempura crumbs, and finely made noodles — honestly, just looking at it makes me drool;;;!!
Where is Kosi Isu Branch, and what are its hours and parking?
Kosi Isu Branch is a 1-minute walk from Exit 9 of Isu Station, so the location is great. Parking is free for 1 hour in the building's underground lot. There are actually quite a few good restaurants in this building, but Kosi always has the longest line (which probably means it's the tastiest). Even during the heat wave, with temperatures around 40°C, there was always a long line in front of the shop. I kept wondering what they were selling that made people wait in line like that!
- 📍Location: 1F 126, 127, 300 Sadang-ro, Dongjak-gu, Seoul, South Korea
- ⏰Hours: Daily 11:20–21:00
- Break time 15:20–17:00
- 1 hour free parking in the building's underground lot
Waiting at 1pm on a Saturday, and the seats inside Kosi
When I arrived around 1pm on a Saturday, the restaurant was already almost full. Right after we got seated, a waiting line started forming behind us. Inside was bigger and cleaner than I expected! There were window seats good for solo dining, plus tables for two and four, so it seemed like a good spot whether you come as a couple or with family.
What's on the menu at Kosi Isu Branch?
Kosi, this tonkatsu place near Isu Station, has udon and tonkatsu as its mains, but looking around at the other customers, more people seemed to be eating udon than tonkatsu.
Since it was my first visit, I ordered to try both the bukkake udon and the tonkatsu! Between the udon topped with fried chicken and the one topped with fried shrimp, I went with the shrimp version and picked the tenbukkake.
- Tenbukkake udon ₩11,000
- Half-and-half tonkatsu ₩13,500
What comes with the 11,000-won tenbukkake udon
The 11,000-won tenbukkake udon comes with fried shrimp, fried sweet pumpkin, and even an inari sushi (fried tofu pocket rice). The noodles in the huge udon bowl look so fine and delicate. The portion is pretty generous too, and it's such a clean setup that you'd get an appreciative "oh~" from anyone you bring here.
Half-and-half tonkatsu, 13,500 won: pork loin and cheese in one plate
The 13,500-won half-and-half tonkatsu comes with both loin katsu and cheese tonkatsu together. It's served with pink salt, wasabi, and tonkatsu sauce.
First off, the portion is seriously generous. Pass.
Let's try the loin katsu first~ The meat is thick and the breading sticks well, so it's a well-fried tonkatsu. Not greasy at all, and the meat was tender!
Cheese katsu, packed full of cheese. You know you have to eat cheese while it's hot, right? If you love cheese, you must order the cheese tonkatsu — it's 10 times more delicious.
A tonkatsu sauce that's perfect for grinding sesame seeds into and dipping deeply!
How do Kosi's house-made bukkake udon noodles taste and chew?
For Kosi Isu Branch's bukkake udon, the broth comes separately. You just pour it all over and mix it up.
The noodles are truly springy, chewy, and dense — chewing them feels almost like eating milddeok (chewy rice cake). And the portion was really generous too. I decided that next time, instead of tonkatsu, I'll just order the cold udon alone. Because that cold udon is so, so, so, so delicious. Best cold udon I've had in recent years.
The fried shrimp that comes with it is seriously plump too. Genuinely delicious — I wanted to eat five of them.
There's even one inari sushi that comes with the udon. Such a generous, value-packed udon from Kosi Isu Branch. All the udon I'd eaten before this wasn't really udon — you can really feel the difference with self-made noodles. The noodles are so dense that even lifting them with chopsticks feels heavy, haha. The texture is so good that I'm definitely coming back whenever I crave cold udon again.
Kosi Isu Branch: the verdict
- Self-made udon noodles are totally chewy
- The tonkatsu is top-notch too
- Clean and spacious interior
- 1 hour free parking in the building's underground lot
Where it is
1F 126, 127, 300 Sadang-ro, Dongjak-gu, Seoul, South Korea서울특별시 동작구 사당로 300 1층 126호, 127호
