In short
Kosi Seongsu (코시 성수점) is a Sanuki udon and tonkatsu restaurant about 115 m from Ttukseom Station Exit 6 (Line 2), a short walk from Seoul Forest. Udon and soba run ₩9,000–11,000 (about $6.40–7.90), and adding a pork cutlet set costs about ₩5,000 more. Open 11:00–21:00 daily with a 15:00–17:00 break. A calm, easy lunch for families and anyone exploring Seoul Forest or Seongsu.
This was a lunch we found in a hurry. We had taken the kids to see a children’s musical at Seoul Forest Theater, and by the time the curtain came down it was exactly lunchtime. I searched for tonkatsu near Seoul Forest on the spot, and Kosi Seongsu came up. It was only about seven minutes away on foot, which made it an easy walk with children in tow.
Kosi is a Japanese-style spot that pairs handmade Sanuki udon with crispy pork cutlets. According to its Naver listing, the name comes from the Japanese word for that springy, chewy bite in good udon noodles, and after this meal I can say the name fits.
Quick facts
- Korean name코시 성수점 (Kosi, Seongsu branch)
- Address1F, 31 Sangwon 1-gil, Seongdong-gu, Seoul
서울 성동구 상원1길 31 1층 - SubwayTtukseom Station (뚝섬역, Line 2), Exit 6, about 115 m. Seoul Forest Station (서울숲역, Suin-Bundang Line), Exit 1, about 5 minutes
- HoursDaily 11:00–21:00, break 15:00–17:00, last order 20:30
- PriceUdon and soba ₩9,000–11,000 (about $6.40–7.90), tonkatsu ₩11,500–14,500, noodle + tonkatsu sets about ₩14,000–16,000
- Good forFamilies with kids, a lunch stop near Seoul Forest, udon and tonkatsu fans
- Phone02-6465-9797
- NotesReservations, takeout and high chairs available. Two free parking spaces in front of the shop (1 hour). Expect a line at weekend lunch.
- MapOpen in Naver Map
Finding it
The closest subway stop is Ttukseom Station on Line 2. Leave by Exit 6 and the restaurant is roughly 115 m away on Sangwon 1-gil. If you are coming from Seoul Forest or Seoul Forest Theater like we were, it is a walk of about seven minutes.
📍 Kosi Seongsu (코시 성수점), 1F, 31 Sangwon 1-gil, Seongdong-gu · Naver Map · Google Maps
Look for a wooden facade with “코시 성수점” written vertically on the wall, and a sidewalk board advertising their ten bukkake udon.
We went on a Sunday at lunchtime, and there was already a line when we arrived. Turnover was not slow, but if you are heading over straight after a show, build in some waiting time.
What we ordered
To make choosing easier, here is how our table worked out. My child picked the zaru soba. I had the maze udon upgraded to a set with tonkatsu, and because it was hot out we also ordered the toriten bukkake udon as a set. One warm noodle to mix, one cold noodle and one light soba meant everyone could try a bit of everything.
One thing to know: at Kosi, tonkatsu comes with noodles when you add a set (정식, jeongsik). According to the menu, a set adds a 120 g pork cutlet to your udon or soba.
1. Zaru soba (자루소바, jaru soba)
My little one ate the cold buckwheat noodles completely plain: no grated radish, no green onion, no wasabi, just noodles dipped in the broth. Even so, I got a big thumbs-up and “this is so good.” The dipping broth was not salty, so it was easy for a child to eat. The tray also came with one piece of inari sushi, and it was nicely plump and filled.
2. Maze udon with a tonkatsu set (마제우동 정식, maje udong jeongsik)
Maze udon is a Japanese-style mixed noodle dish: thick noodles topped with seasoned minced meat and other toppings, which you toss together with the sauce. The noodles were wonderfully bouncy. The egg yolk on top was fresh, and once I mixed it into the sauce the flavor of the noodles really came through. This is the one I would recommend without hesitation.
For the tonkatsu, I ground plenty of sesame seeds into the dipping sauce, and it made the sauce noticeably better. The cutlet was thick, which could easily feel heavy, but it was not greasy at all, just nutty and savory. A small dab of wasabi on each bite kept things fresh.
3. Toriten bukkake udon set (토리텐붓카케우동 정식, toriten butkake udong jeongsik)
It was a hot day, so cold udon was calling. Bukkake udon is chilled noodles that you dress with a small amount of cold tsuyu (soy-based sauce) rather than a full bowl of soup, and “toriten” means it comes topped with fried chicken. We poured the sauce over so the noodles were just coated, then added tempura flakes and green onion.
The chewy noodles soaked up the sauce beautifully, and they stayed firm right to the last bite. We shared the fried chicken with the kids, and they ate it well. Even the sliced cabbage on the side was tasty with a spoonful of the sauce on top.
Menu and prices
*USD figures are rough estimates at about ₩1,400 to $1. Single-dish prices are from Naver Place (menu updated April 2026). Set prices are from the printed menu at our visit, since Naver does not list them. Prices can change.
Tips for visitors
- Mind the break time. The kitchen closes from 15:00 to 17:00, so a late lunch after a matinee needs some planning.
- Expect a weekend line. We waited at Sunday lunch; turnover was steady.
- Want tonkatsu and noodles? Order a set (jeongsik), which adds a cutlet to your udon or soba.
- Grind the sesame. Add plenty of ground sesame to the tonkatsu sauce, and try a little wasabi on the cutlet.
- Bukkake udon tip: pour the cold sauce in gradually and mix as you go, then add tempura flakes and green onion to taste.
- Parking. There are only two free spaces in front of the shop for one hour, so the subway is easier.
- Ordering phrase: “Jeongsik-euro juseyo” (정식으로 주세요) means “Make it a set, please.”
Is it kid-friendly?
Yes, in our experience. The atmosphere is calm, the broths and sauces are not harsh, so picking something for the kids was easy, and Naver lists high chairs. Being able to share udon, soba and tonkatsu at one table also makes it a good fit for families who all want something different.
My verdict
If you are looking for tonkatsu near Seoul Forest and want great udon on the same tray, I would happily recommend Kosi Seongsu. The noodles have real bounce, the cutlet is thick without being greasy, and it is a calm place to eat with kids. Just allow for a wait on weekends. Next time we are around Seoul Forest, I would like to go back.
Kosi Seongsu FAQ
Where is Kosi Seongsu?
Kosi Seongsu is on the ground floor of 31 Sangwon 1-gil, Seongdong-gu, Seoul. Naver puts it about 115 m from Exit 6 of Ttukseom Station (Line 2), and the restaurant says it is about a five-minute walk from Exit 1 of Seoul Forest Station. From Seoul Forest Theater it took us around seven minutes on foot.
What are Kosi Seongsu’s opening hours?
Naver lists Kosi Seongsu as open every day from 11:00 to 21:00, with a break from 15:00 to 17:00 and last order at 20:30.
What is a “set” (jeongsik) at Kosi Seongsu?
At Kosi Seongsu you can upgrade an udon or soba to a set, which adds a 120 g pork cutlet (tonkatsu) to the tray. If you want tonkatsu with your noodles, this is the easiest way to get both.
Is there a wait at Kosi Seongsu?
We arrived at Sunday lunchtime and there was already a line. It moved at a reasonable pace, but on weekends, especially right after a show at Seoul Forest Theater, plan for some waiting time.
Is Kosi Seongsu good for kids?
It was for us. The room is calm, the broths and sauces are not harsh, and Naver lists high chairs. My child loved the plain zaru soba, and the kids happily shared the fried chicken from our cold udon.
More easy family meals: try Sammi Tantanmyeon in Sinchon for honey chashu lo mein, or Namaste Dongmyo for mild Indian curry by the toy street. See all kid-friendly restaurant guides and Seoul restaurant guides.
More places nearby
Visited: August 2026. Prices and hours last checked: October 20, 2026, on Naver. Please check Naver Map before you go.
This post is based on my own visit and photos. I used AI tools to help with the English wording.