Seongsu tonkatsu restaurant with zaru soba set and karaage don: Kosi

Hi, I'm Ddoromi :) Today I'm introducing an incredible value-for-money Japanese restaurant in Seongsu — perfect for solo dining, lunch, or a date! 🤤 It's a Seongsu tonkatsu spot that actor Kim Seung-soo raved about, and it's also been featured on SBS's Life's Grand Masters.

To cut to the conclusion first: this was the best tonkatsu I've ever had, hands down, and every single dish I ordered was so satisfying that I just had to share it .. ´͈ ᵕ `͈ It's the Seongsu tonkatsu restaurant "Kosi" — Seongsu Branch!

How to find Kosi Seongsu Branch, and is there a wait?

Kosi Seongsu Branch is within 100m (about a 1-minute walk) from Ttukseom Station Exit 6, and about 5 minutes from Seoul Forest Station Exit 1, so it's really easy to find and get to. As a well-known Seongsu tonkatsu spot, there's even a waiting list sign-up station set up outside the store.

Every time I've passed by there's been a wait, but this time the timing worked out and I got in lucky, with no wait at all ,,☘️ The turnover is fast, so don't worry too much about it - ( ̳• ·̫ • ̳) I got curious about what "Kosi" means, and apparently in Japan it describes a satisfying chewiness in food!

Inside Kosi Seongsu Branch: solo seats, group tables and an open kitchen

The interior of Kosi Seongsu Branch is bright, clean and comfortable overall, with both solo-dining seats and group seats, so it looked great for a date, solo lunch, or eating with a group!

It's also an open kitchen, so you can see for yourself how cleanly the kitchen is kept, and watching the cooking happen right in front of you made me trust the place even more.

What we ordered at Kosi Seongsu Branch and what it cost

You can conveniently order via kiosk at each table. Here's what we ordered.

• Mixed katsu (+ set upgrade to kake udon ₩3,500) ₩14,500
• Zaru soba (+ set upgrade to tonkatsu ₩5,000) ₩11,000

Since it's a great-value Japanese restaurant, the price for upgrading to a full set was also very reasonable!

Kosi Seongsu Branch hours and parking

• Hours: (Mon-Sun) 11:00 - 21:00 (last order 20:30), break time 15:00 - 17:00
• Parking: available / 2 spots in front of store, free for 1 hour
• If full, use nearby public parking lots (paid) — Seongsu Culture & Welfare Center / Seongdong District Sports Center public lots

There's also a Naver coupon, so make sure to grab that - ✨

Mixed katsu set: tonkatsu, king shrimp katsu, udon and salad

First up is the mixed katsu set 🦐 It comes with tonkatsu, king shrimp katsu, udon, and salad all together. Such an insanely good-value, filling combo, right? 😳

Kosi, the Seongsu tonkatsu spot, uses domestic fresh pork loin that's pounded fresh every day, and it's fried as soon as it's ordered. I took a bite and honestly.. this was the best Japanese tonkatsu I've ever had.. (my partner agreed too). The breading was genuinely crispy and the inside was so, so tender — perfectly crispy-outside-tender-inside, and I just kept eating more... You seriously have to try this .. please do .. (for real)

The Sanuki udon that comes with the set is the real surprise

The king shrimp was really big and plump, and doesn't the crispiness of the batter come through just from the photo..?🥹 And the udon that came with it was also insane.. I regretted not ordering udon on its own too ... A lot of other tables were ordering udon as a standalone dish.

Kosi's tonkatsu is amazing, but the udon is actually what's really famous — they say it's simmered in soy sauce imported directly from Japan, and they only use fresh noodles made with the 800-year-old traditional Sanuki method, using anchovies and kelp sourced directly from Namhae. The noodles are kneaded with just three ingredients — salt, water, and flour — following the traditional Sanuki method (the udon kingdom), then go through a first and second fermentation before being finished after 48 hours. That's probably why the noodles have such a chewy, springy texture. Isn't that just so much dedication..?!🥹 I'm definitely getting the standalone udon next time .. .ᐟ.ᐟ

Zaru soba set: cold soba with tonkatsu and inari sushi

And to close out the last of summer, the zaru soba set appeared! You can adjust the flavor to taste with scallion, wasabi, and grated radish, and the soba noodles had a springy, chewy texture that was nutty and clean even on its own — but dipped into the cold, umami-rich tsuyu sauce, it was clean, refreshing, and deeply flavorful.. 👍🏻

Eating it together with the inari sushi and tonkatsu that came with the set made it even better .. seriously, what isn't good here .. !!!!!!! ╥﹏╥

Karaage don, 10,500 won

Everything on the menu was delicious, so even though we were full, we ordered the garaage-don anyway — ₩10,500. It's a rice bowl piled with crispy fried chicken thigh, onion sauce, a special sauce, and a generous amount of soft egg. The chicken thigh portions were really generous and the amount of food was huge — it wasn't too heavy or overpowering, and it was seriously filling. I basically demolished the whole thing and nearly burst .. but I was happy ..

Is Kosi Seongsu Branch worth it for a Seongsu lunch or date?

If you're looking for a satisfying lunch in Seongsu, planning a Seongsu date or just wandering around Seongsu and want something delicious, or if you're searching for a good Seoul Forest restaurant or Ttukseom restaurant, I highly recommend the Seongsu tonkatsu spot "Kosi" — you really should visit .ᐟ.ᐟ It might just become the best tonkatsu of your life .. ✨ Next time I'm definitely getting the udon set ..! 🥹