# Seongsu udon restaurant, 5 dishes for two at mid-30,000 won: Kosi

- By Eungyeol (https://superchart.com/en/@daejeon-quiet-plate/)
- Written Sep 6, 2026
- Local places › Restaurants › Seongdong, Seoul
- Sponsored: This is a post written after receiving a complimentary meal from the restaurant.
- English edition: https://superchart.com/en/@daejeon-quiet-plate/koshi-seongsu-tonkatsu-udon-two-people/
- Also in: [한국어](https://superchart.com/ko/@daejeon-quiet-plate/koshi-seongsu-tonkatsu-udon-two-people/index.md)

## In short

Kosi Seongsu Branch is a handmade sanuki udon and tonkatsu restaurant in an alley in Seongdong, Seoul, closer to Ttukseom Station than Seongsu Station. Two diners ordered 2 mains — half-and-half katsu and tori-ten bukkake udon — plus 3 sides of lotus root kushikatsu, shrimp tempura and squid rings, and the bill came to the mid 30,000 won range, with katsu that tastes far better fried to order than by delivery. Between the value and the room itself, Kosi Seongsu Branch is an easy recommendation for Japanese tonkatsu and udon around Seongsu and Ttukseom.

## Good to know

- **Location**: 31 Sangwon 1-gil, 1st floor, Seongdong-gu, Seoul (closer to Ttukseom Station than Seongsu Station)
- **Hours**: Daily 11:00–21:00
- **Break time**: 15:00–17:00
- **Last order**: 20:30
- **Services**: Takeout, delivery, groups, reservations and parking available
- **Parking**: Up to 2 cars in front of the restaurant
- **Seating**: Solo, 2-person and 4-person tables
- **What we ordered**: Half-and-half katsu, tori-ten bukkake udon, lotus root kushikatsu, shrimp tempura, squid rings
- **Side price**: 4,000 won each
- **Bill for two**: 2 mains + 3 sides, mid 30,000 won range
- **Review event**: Choice of a fried side, such as lotus root kushikatsu or croquette
- **Price reference**: ₩30,000 ≈ $22.5 · ₩4,000 ≈ $3 (2026-09-15)

*as written by the visitor on Sep 6, 2026*

![Half-and-half katsu and udon, the signature dishes at Kosi Seongsu Branch](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-01-10mhx-1200.webp)

Today I visited Kosi, a handmade udon and tonkatsu specialist in Seongsu, known for great tonkatsu! I'd ordered delivery from another branch many times but this was my first time actually visiting a Kosi restaurant, so I came in with high expectations — and it exceeded them, haha!

![Exterior of Kosi Seongsu Branch in the alley near Ttukseom Station](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-02-10wnh-900.webp)

## Where is Kosi Seongsu Branch, and what are its hours?

- Address: 31 Sangwon 1-gil, 1st floor, Seongdong-gu, Seoul, South Korea
- Hours: Daily 11:00–21:00
- Break time 15:00–17:00 / Last order 20:30
- Takeout, delivery, groups, reservations, and parking all available

This Seongsu tonkatsu favorite, Kosi Seongsu Branch, is actually closer to Ttukseom Station than Seongsu Station. It's not crowded at all, so the alley has a relaxed, quiet vibe that made it much easier to find — a lot more pleasant than the busy main streets. There's parking for up to 2 cars right in front too, so it's easy to get to whether you drive or take transit!

![View of the alley in front of Kosi Seongsu Branch](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-03-1g65s-900.webp)

![Interior view of solo and 2-person seating at Kosi Seongsu Branch](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-04-1c21y-900.webp)

![Interior view of a 4-person table at Kosi Seongsu Branch](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-05-mv9hc-m-900.webp)

## Does Kosi Seongsu Branch have seats for solo diners?

Inside, Kosi Seongsu Branch has not just solo seats but 2-person and 4-person tables too, so it felt comfortable whether you come alone or with a group. It'd be a great spot if you're in Seongsu or Ttukseom and hesitating over eating alone.

From their signature cold udon to hot udon, tonkatsu, and donburi (rice bowl), they had a range of Japanese dishes, plus plenty of sides to order to your taste.

![Menu board listing cold udon, hot udon, tonkatsu, and donburi](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-06-11n1h-900.webp)

## Review event: pick a fried side at Kosi Seongsu Branch

They were also running a Naver review event, and instead of just one fixed item, you could choose from several options like lotus root kushikatsu (skewered fried lotus root) or croquette. Most places just give you a drink, so being able to pick a fried side you actually like felt like a real bonus! Definitely take part if you visit.

![Sign for Kosi Seongsu Branch's Naver review event](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-07-a1pa3-900.webp)

## Two mains and three sides for two: mid 30,000 won

We came as two people — 2 mains, 3 sides, right? There was so much I wanted to try that we ordered all of it, and even so the total came out to just mid ₩30,000s! With value like that, there's really no reason not to come here...

![Salad dressing and cutlery set out on the table](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-08-pbd30-900.webp)

Each table had salad dressing and the necessary cutlery neatly set out. It was nice being able to pour on as much dressing as you liked, and the cutlery and table were spotlessly clean, which was a great first impression.

![Complimentary cheese sweet potato croquette](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-09-1iuvb-900.webp)

A complimentary cheese sweet potato croquette on the house.. it's a small thing, but it really made my day!

![Table set with half-and-half katsu, udon, and sides](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-10-vn3cm-900.webp)

![Full spread of 2 mains and 3 sides on the table](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-11-1b2gq-900.webp)

## The full order at Kosi Seongsu Branch

- Half-and-half katsu
- Lotus root kushikatsu
- Tori-ten bukkake udon
- Squid rings

![Half-and-half katsu with tonkatsu and cheese katsu](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-12-6zfiv-900.webp)

### Half-and-half katsu: tonkatsu and cheese katsu on one plate

The half-and-half katsu at Kosi Seongsu Branch pairs regular tonkatsu with cheese katsu, so you get both the light, crispy classic and the rich, savory cheese version — a total two-birds-one-stone dish! If you can't decide, half-and-half is the way to go.

![Cross-section of the cheese katsu with cheese stretching out](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-13-2vzcd-900.webp)

Look at that cheese pull. It just kept stretching endlessly, and the visual alone was amazing! Crispy on the outside, packed full of mozzarella on the inside — I let out a gasp with the very first bite.

![Cross-section of the crispy-breaded tonkatsu](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-14-147p9-900.webp)

The tonkatsu wasn't dry at all and had no off smell, so you could really feel how juicy it was. The breading had zero stale-oil smell and stayed crispy all the way through — a little salt or wasabi on top made it taste incredible.

![Tori-ten bukkake udon with noodles and tsuyu served separately](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-15-rvnj7-900.webp)

### Tori-ten bukkake udon: 3 pieces of fried chicken and sanuki noodles

For the tori-ten bukkake udon, the noodles and tsuyu (dipping/soup broth) came separately, and it also came with one piece of inari (fried tofu pouch) sushi!

![Three large pieces of fried chicken on top of the tori-ten](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-16-nj0e4-900.webp)

There were three big pieces of fried chicken on top. It had a strong handmade fried chicken feel, worlds apart from your average karaage — crispy outside, juicy inside, and the juices burst out the moment you bit in! The seasoning was perfectly salty too, an absolutely dreamy match with the udon noodles.

![Sanuki-style udon noodles doused in tsuyu](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-17-1gwm6-900.webp)

Kosi's noodles are made using the Udong Wanggun traditional sanuki method, so the udon strands had a real chewy, springy bounce. Pouring the cool tsuyu over them kept that bouncy, chewy texture alive all the way to the last strand — I finished it without getting tired of it once.

![Side dishes of lotus root kushikatsu and shrimp tempura](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-18-1ditz-900.webp)

![A plate of freshly fried side dishes](https://img.superchart.com/images/koshi-seongsu-tonkatsu-udon-two-people/koshi-seongsu-tonkatsu-udon-two-people-19-1f345-900.webp)

## The 4,000 won sides: lotus root kushikatsu, shrimp tempura, squid rings

The sides we ordered separately — lotus root kushikatsu and shrimp tempura, plus squid rings (not pictured) — were all ₩4,000 each, which felt hard to believe given the quality. True to its reputation as a Seongsu tonkatsu favorite, the breading was thin and crispy so nothing felt greasy, and the natural flavor of each ingredient really came through. The crunchy lotus root and the springy squid rings especially were great little bites to snack on between mains.

After only ever having it delivered, eating fresh-fried katsu and bouncy handmade udon straight from the kitchen at Kosi Seongsu Branch was so much more delicious and satisfying! Great value, a comfortable atmosphere — I genuinely recommend it if you're looking for a proper Japanese tonkatsu and udon spot in Seongsu or Ttukseom!

## Where it is

- Kosi Seongsu Branch (코시 성수점)
- 31 Sangwon 1-gil, 1st floor, Seongdong-gu, Seoul, South Korea
- 서울특별시 성동구 상원1길 31 1층
- 37.5464155, 127.0474867
- Google Maps: https://www.google.com/maps/search/%EC%BD%94%EC%8B%9C%20%EC%84%B1%EC%88%98%EC%A0%90/@37.5464155,127.0474867,17z

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