# Seongsu restaurant for tonkatsu and cold udon: Kosi

- By Naeun (https://superchart.com/en/@seoul-bap-bench/)
- Written Sep 11, 2026
- Local places › Restaurants › Seongdong, Seoul
- Sponsored: This post was written with support for a restaurant visit.
- English edition: https://superchart.com/en/@seoul-bap-bench/seongsu-koshi-cold-udon-katsu/
- Also in: [한국어](https://superchart.com/ko/@seoul-bap-bench/seongsu-koshi-cold-udon-katsu/index.md)

## In short

Kosi Seongsu Branch is a Japanese restaurant in Seongdong, Seoul, near Ttukseom Station. I ordered tempura bukkake udon, half-and-half katsu, shrimp tempura, and lotus root kushikatsu for a satisfying mix of cold noodles and crisp fried dishes. Kosi Seongsu Branch is a great stop for a hearty Seongsu date meal.

## Good to know

- **Location**: 9-9 Seongsu-dong 1-ga, Seongdong-gu, Seoul
- **Hours**: Daily 11:00–21:00
- **Break time**: 15:00–17:00
- **Ordered**: Tempura bukkake udon, half-and-half katsu, shrimp tempura (2 pieces), lotus root kushikatsu (3 pieces)

*as written by the visitor on Sep 11, 2026*

![A full spread of tonkatsu and udon at Kosi Seongsu Branch](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-01-1qu3k-1200.webp)

Today, I’m introducing a place I visited because I wanted to have tonkatsu and udon together in Seongsu. There are so many great places to eat in Seongsu that I had a hard time deciding, but that day I went to Kosi Seongsu Branch (코시 성수점), where you can enjoy Japanese-style tonkatsu and udon together. Especially when the weather is hot like it has been lately, you keep craving cold udon rather than warm udon, right? So I properly ordered a tonkatsu dish along with bukkake udon and enjoyed it all!

## How long does it take to get to Kosi Seongsu Branch from Ttukseom Station?

Kosi Seongsu Branch is about a two-minute walk from Exit 6 of Ttukseom Station. It is close to the station, so it seemed convenient for meeting up, too.

## The exterior and atmosphere inside

![Exterior of Kosi Seongsu Branch, a Seongsu restaurant known for tonkatsu](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-02-1btfb-900.webp)

This is the exterior of Kosi, a Seongsu spot known for tonkatsu.

![Waiting list outside Kosi Seongsu Branch](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-03-wjkmu-900.webp)

There was a waiting list in front of the restaurant. We visited near the end of lunch hours and luckily got in right away, but it seems there is often a wait at weekday lunch.

![Overview of the dining room at Kosi Seongsu Branch](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-04-1r9it-900.webp)

![Neatly arranged interior of Kosi Seongsu Branch](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-05-14w1h-900.webp)

As soon as we stepped inside, it had such a neat Japanese restaurant feel. It was tidily arranged but still atmospheric, giving it that proper Seongsu dining-out vibe.

![Bar-table seating at Kosi Seongsu Branch](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-06-ljss8-900.webp)

We took seats at the bar table.

![Bar table set with water and sauces](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-07-hiaji-900.webp)

Water and sauces were set out at every seat, and ordering through the kiosk was easy, so the whole ordering process was simple.

## Kosi Seongsu Branch menu

![Menu guide at Kosi Seongsu Branch](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-08-uu3ht-900.webp)

![Kosi Seongsu Branch menu selection](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-09-gb18q-900.webp)

Here is the menu at Kosi Seongsu Branch.

## Ordering tempura bukkake udon and half-and-half katsu

- Tempura bukkake udon
- Half-and-half katsu
- Shrimp tempura (2 pieces)
- Lotus root kushikatsu (3 pieces)

![Ordered tempura bukkake udon and half-and-half katsu](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-10-1ghl7-900.webp)

### Tempura bukkake udon and lotus root kushikatsu

![Tempura bukkake udon paired with lotus root kushikatsu](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-11-eovmn-900.webp)

### Half-and-half katsu and shrimp tempura

![Half-and-half katsu paired with shrimp tempura](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-12-wyakb-900.webp)

## Tempura bukkake udon that was perfect for a hot day

First, the tempura bukkake udon that I especially enjoyed that day! It is cold udon topped with crisp tempura. It was absolutely perfect for a hot summer day.

![Tempura-topped bukkake udon](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-13-9rxdu-900.webp)

First, pour in the cold broth.

![Pouring cold broth over bukkake udon](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-14-ioor7-900.webp)

![Cold, springy udon noodles](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-15-ed6yj-900.webp)

The cold, springy udon noodles were amazing! They were bouncy and chewy, so you could feel the noodles’ elasticity with every bite. Served cold, the broth tasted clean, and it definitely felt lighter in hot weather.

![Cold udon served with crisp tempura](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-16-14le6-900.webp)

The lotus root kushikatsu (skewered fried cutlet) was on the soft side! I expected fried lotus root to be firm and crunchy, but it was soft. As I chewed, its nutty lotus-root flavor came through, and it was nice.

![Soft lotus root kushikatsu](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-17-wi53t-900.webp)

## Half-and-half katsu with pork loin and cheese

The half-and-half katsu lets you enjoy pork loin katsu and cheese katsu at the same time.

![Half-and-half katsu with pork loin and cheese katsu](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-18-1jkhn-900.webp)

The cheese tonkatsu was packed with cheese. This is exactly the look you want from cheese tonkatsu >,<

![Cheese tonkatsu filled generously with cheese](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-19-1ecet-900.webp)

I topped the crisp pork loin tonkatsu with sauce and wasabi, yum~~ As you would expect from a place known for tonkatsu in Seongsu, the crisp coating and the pork loin’s chew were something else.

![Pork loin tonkatsu topped with sauce and wasabi](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-20-8c70i-900.webp)

The cheese tonkatsu was even tastier with the cheese’s soft, rich nuttiness, haha. The cheese tonkatsu was more my style.

![Cross-section of rich, nutty cheese tonkatsu](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-21-1ho18-900.webp)

![Shrimp tempura enjoyed with bukkake udon](https://img.superchart.com/images/seongsu-koshi-cold-udon-katsu/seongsu-koshi-cold-udon-katsu-22-kk7g2-900.webp)

## Adding shrimp tempura to bukkake udon

The extra shrimp tempura was a great pairing with the bukkake udon, haha. After eating cold noodles continuously, having warm, crispy shrimp tempura in between changed up the texture completely, which I loved. I definitely recommend adding it as a side~~

## My overall thoughts on Kosi Seongsu Branch

Kosi Seongsu Branch is a good place to visit when you want tonkatsu and cold udon together. The fresh pork loin half-and-half katsu was nice because I could try both the classic katsu and cheese katsu at once, while the tempura bukkake udon was satisfying with chewy noodles and crispy tempura. It is also close to Ttukseom Station, making it a lovely Seongsu tonkatsu spot for a filling meal during a date in Seongsu~~

## Where it is

- Kosi Seongsu Branch (코시 성수점) (코시 성수점)
- 31 Sangwon 1-gil, 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

---

Superchart · https://superchart.com/en/@seoul-bap-bench/seongsu-koshi-cold-udon-katsu/ · https://superchart.com/llms.txt