Seongsu katsudon restaurant with rainy-day bar seats: Kosi Seongsu
In short
Kosi Seongsu Branch is a tonkatsu and udon restaurant in Seongdong, Seoul, one minute from Exit 6 of Ttukseom Station. Seated at the bar table facing the kitchen on a rainy day, the writer ordered the toriten bukkake udon set with tonkatsu at 16,000 won, the signature handmade katsudon set with udon at 14,500 won and whole squid rings, and the katsudon kept an even layer of onion and fluffy egg from the first bite to the last. The katsudon and the fried dishes at Kosi Seongsu Branch are worth a return trip.
Good to know
- Toriten bukkake udon set (with tonkatsu)
- 16,000 won (base 11,000 won + tonkatsu add-on 5,000 won)
- Signature handmade katsudon set (with udon)
- 14,500 won (base 11,000 won + udon add-on 3,500 won)
- Whole squid rings, 3 pieces
- 4,000 won
- Pepsi Zero
- 2,000 won
- Bukkake udon
- 9,000 won
- Standard dishes
- Mostly 11,000 won, upgradeable to a set
- Location
- 1 minute from Ttukseom Station Exit 6, 5 minutes from Seoul Forest Station Exit 1
- Parking
- 2 spaces in front of the restaurant, free for 1 hour
- Seating
- Two 8-person tables, one 2-person table by the window, 9 bar seats
- Ordering
- Order and pay at the kiosk on the table
as written by the visitor on Sep 6, 2026
A rainy day walk over to Ttukseom Station
I was hanging out in Seongsu on a rainy day, but taking the subway from Seongsu Station felt exhausting with how crowded it gets, so I moved toward Ttukseom Station instead. I was super ~~ hungry, so I searched for a good tonkatsu spot near Ttukseom Station and found Kosi Seongsu Branch, which had both udon and katsu — perfect, off I went.
It's a 1-minute walk from Exit 6 of Ttukseom Station, and 5 minutes from Exit 1 of Seoul Forest Station, so it's easy to reach on foot either way.
Is there parking at Kosi Seongsu?
Kosi Seongsu Branch has 2 free parking spots in front for 1 hour. When I visited, both spots were already taken.
Inside Kosi: the space and the bar table
Two 4-person tables are pushed together to seat 8 people (two of these 8-person setups total), and there's one 2-person table by the window.
There's also a bar-style seating area facing away, with 9 seats total.
I sat at the bar table right in front of the kitchen so I could watch the steam rising ∗´ര ᎑ ര`∗ There's a kiosk right at the table, so you just order and pay directly.
What we ordered and what it cost
Toriten bukkake udon Katsudon
- Toriten bukkake udon set (with tonkatsu) ₩16,000 — base ₩11,000 upgraded to a set with tonkatsu added > +₩5,000
- Signature handmade katsudon set (with udon) ₩14,500 — base ₩11,000 upgraded to a set with udon added > +₩3,500
- Whole squid rings (3pc) ₩4,000
- Pepsi Zero ₩2,000
The signature bukkake udon is ₩9,000 on its own. Most base menu items are ₩11,000 and can be upgraded to a full set.
Toriten bukkake udon: chewy cold noodles with chicken tempura
The cold udon comes with a soy-based sauce, and you add the accompanying toppings to your taste. The noodles were remarkably chewy and springy with real bite. It was surprising — so different from the slurp-it-right-down udon I usually eat, with a real chewy texture instead. The udon and the karaage that came with it were both seriously delicious.
The tonkatsu came with wasabi and tonkatsu sauce on the side, plus pickled radish and diced kkakdugi (radish kimchi) as side dishes.
Plump, fat inari sushi and crispy tonkatsu. No gamey smell at all, and the tonkatsu was thick-cut with really good frying. This is definitely a tonkatsu spot — and a fried food spot — worth knowing near Ttukseom Station. Even the sauce that came with it wasn't store-bought, which I really appreciated!
What happens when you add hot udon to the katsudon set?
The katsudon set with hot udon added. The portion of udon that comes as a set add-on was as generous as a standalone order. The noodles were super chewy too. Since the broth is hot, the noodles felt a touch softer than the cold udon version. The fried squid was really delicious. Every fried item here, from the batter to what's inside, is packed and tasty, so I highly recommend it.
This katsudon (pork cutlet rice bowl) is genuinely the best I've ever had. The egg was perfectly fluffy and soft, spread evenly across the whole bowl. The tonkatsu meat was fried tender and delicious, with sauce soaked in evenly, so you could just dig straight down from the top. Usually by the end you're left with just rice and tonkatsu, but here the onions were piled thick all the way through, just like in the photo. Genuinely touched by that.. I care a lot about getting the right ratio in every bite, so being able to eat all the ingredients evenly from start to finish was really satisfying.
The cabbage that came with it had no sauce of its own — you just drizzle on the sauce provided at the table.
Why I would recommend Kosi Seongsu Branch
- Close to the station
- 2 free parking spots in front of the restaurant
- Staff are very kind
- Bar seating that's great for solo dining
- Group bookings for up to 10 people are possible
- Clean restaurant with a restroom right next to the store
- Generous portions and good quality for relatively affordable prices
- Katsudon and fried dishes are seriously delicious
I visited on a rainy day, the staff were kind, and I enjoyed the katsudon a lot. I'll definitely be back for more katsudon next time.
Where it is
31 Sangwon 1-gil, 1F, Seongdong-gu, Seoul, South Korea서울특별시 성동구 상원1길 31 1층
