# Seongsu tonkatsu lunch with shichimi udon at a solo counter: Kosi - By Sunwoo Baek (https://superchart.com/en/@dongmyo-late-plate/) - Written Sep 20, 2026 - Local places › Restaurants › Seongdong, Seoul - Sponsored: This post was written after receiving a complimentary store visit as sponsorship. - English edition: https://superchart.com/en/@dongmyo-late-plate/koshi-seongsu-solo-lunch-katsu/ - Also in: [한국어](https://superchart.com/ko/@dongmyo-late-plate/koshi-seongsu-solo-lunch-katsu/index.md) ## In short Kosi Seongsu Branch is a Japanese restaurant on Sangwon 1-gil in Seongdong, Seoul, serving Sanuki-style handmade udon and tonkatsu (breaded pork cutlet). Looking for a solo lunch in Seongsu, the writer ordered the mixed katsu set — regular tonkatsu plus cheese katsu with hot udon — and finished the broth after adding shichimi (Japanese seven-spice). With dedicated solo-dining seats, Kosi Seongsu Branch is an easy, quick lunch with no self-consciousness about eating alone. ## Good to know - **Hours**: Daily 11:00-21:00 - **Break time**: 15:00-17:00 - **Ordered**: Mixed katsu set (regular tonkatsu + cheese katsu, hot udon included) - **Main menu**: Tonkatsu, bukkake udon, soba, udon - **Seating**: Solo-dining seats available - **Options**: Extra udon or extra tonkatsu can be added to each menu item *as written by the visitor on Sep 20, 2026* ![Signature photo of Kosi Seongsu Branch](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-01-1eioi-1200.webp) There are so many good restaurants in Seongsu that I always agonize over where to go for lunch!!! Especially when eating alone, I tend to look for a place where I can sit comfortably rather than somewhere crowded with a long wait, haha. Here's my review of Kosi, a great spot for a solo lunch in Seongsu!! ## Kosi Seongsu Branch opening hours - Daily 11:00-21:00 - Break time 15:00-17:00 ## What's on the menu at Kosi in Seongsu ![Menu board at Kosi Seongsu Branch](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-02-7v65n-900.webp) ![Menu guide for tonkatsu and udon dishes at Kosi Seongsu Branch](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-03-2t2sj-900.webp) Seongsu-dong has a lot of office workers, so restaurants get packed at lunchtime, and eating alone in some places can feel a bit awkward. But Kosi has solo-dining seats, so you can eat comfortably — I'd definitely recommend it to anyone looking for a solo lunch spot in Seongsu!! ![Interior of Kosi Seongsu Branch with solo-dining seats](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-04-1ke7o-688.webp) ![View of the seating area at Kosi Seongsu Branch](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-05-sv7j8-684.webp) ### Sanuki-style handmade udon noodles at Kosi The main menu items here are tonkatsu, bukkake udon, soba, and udon. The noodles are made from just three ingredients — salt, water, and flour — and the dough goes through a first and second fermentation over 48 hours. This is apparently the traditional method from Sanuki, the udon kingdom of Japan!! The noodles are chewy with a tension like a perfectly tuned string instrument. In Japan, they'd describe it as having good 'koshi' (bite)!! ![Sign explaining the Sanuki-style handmade udon noodles](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-06-1ukny-900.webp) ![Sign explaining the extra options available for each menu item](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-07-1ul64-900.webp) You can also add extras to most menu items — extra udon, extra tonkatsu, and so on — so you can enjoy a variety of dishes in a really generous portion, haha. ![The full spread of the mixed katsu set](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-08-1t8l0-900.webp) ## Mixed katsu set: tonkatsu and cheese katsu on one plate I ordered the mixed katsu set, which comes with a regular hot udon on the side! The mixed katsu comes with both regular tonkatsu and cheese katsu, so it's perfect if you want to try a bit of everything. ![Crispy fried regular tonkatsu](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-09-1r8ft-900.webp) ![Salad and rice served alongside the tonkatsu](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-10-1snv5-900.webp) Since the pork is aged, it was incredibly tender and delicious — not the least bit dry, and nicely crispy. The salad and rice that came with it went really well together too. ![Cross-section of sliced tonkatsu](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-11-1so0n-900.webp) ### Cheese katsu with cheese pouring out like a waterfall The cheese katsu was tonkatsu with cheese pouring out like a waterfall — this was genuinely the dish I enjoyed the most!! Honestly, if I come back, I'd want to order the cheese katsu again — the balance of cheese and meat was that good, haha. ![Cheese katsu with cheese flowing out](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-12-1tdf9-900.webp) ![Mozzarella cheese stretching from the cheese katsu](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-13-i0es6-900.webp) Can you see how well the cheese stretches?! Even the mozzarella alone was really tasty. ![Hot udon served with the set](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-14-uvjgk-900.webp) ## The hot udon that comes with the set, plus shichimi True to being handmade udon, it had a really clean, light flavor that was easy to eat. Next time I'd like to try the cold udon or the bukkake udon, haha. ![Udon broth with shichimi added](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-15-1clnh-900.webp) ![Lifting up a bundle of udon noodles](https://img.superchart.com/images/koshi-seongsu-solo-lunch-katsu/koshi-seongsu-solo-lunch-katsu-16-m9pf1-900.webp) I like my food spicy, so I added some shichimi, and the seasoning turned out just right. Drinking the broth along with it left me perfectly full. ## Is Kosi Seongsu Branch a good solo lunch spot in Seongsu? With this many menu options for solo dining, Kosi in Seongsu doesn't feel awkward to visit alone, and it's also great for a quick lunch. If you're looking for a solo lunch spot in Seongsu, I'd say it's worth adding to your list. I'd recommend it to anyone looking for a place to eat alone in Seongsu or a good lunch spot for office workers! I'd definitely come back next time I'm having lunch alone in Seongsu +_+ ## Where it is - Kosi Seongsu Branch (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/@dongmyo-late-plate/koshi-seongsu-solo-lunch-katsu/ · https://superchart.com/llms.txt