Tonkatsu restaurant near Isu Station: cold udon lunch for two at Kosi
In short
Kosi Isu Branch is a house-made bukkake udon and tonkatsu restaurant on the first floor of the Isu Xi mixed-use building by Exit 9 of Isu Station in Dongjak, Seoul. On a weekday at 1pm, after a hospital visit, the writer shared cold udon and mixed tonkatsu with her sister who lives nearby, and the chewy Sanuki-style noodles played nicely against the thick, crisp pork loin cutlet. At Kosi Isu Branch, order bukkake udon rather than the hot udon to taste the noodle texture, and choose a set that comes with tonkatsu.
Good to know
- Location
- 1st floor, units 126 and 127, 300 Sadang-ro, Dongjak-gu, Seoul (1st floor of the Isu Xi mixed-use building)
- Getting there
- 119m from Exit 9 of Isu Station (Lines 4 and 7), first floor of the building with McDonald's
- Note
- The Exit 9 escalator is under construction, so use another exit
- Parking
- Isu Xi complex mall, basement levels 2-3, 1 hour free
- What we ordered
- Cold udon (bukkake udon), mixed tonkatsu
as written by the visitor on Sep 16, 2026
Mrs. Po here — somehow I've been eating out every single day lately haha. Today I went to the hospital early in the morning, and just thinking about cooking lunch for myself at home exhausted me. I'd been to Kosi Isu Branch before, a great spot for solo dining near Isu Station, so I thought I'd just go grab a bukkake udon by myself. Then my sister, who lives nearby, said she'd never been to KOSHI either, so she joined me~ The two of us ended up eating tonkatsu and udon together.
Where is Kosi Isu Branch, and what's happening at Isu Station Exit 9?
Kosi Isu Branch is 119m from Exit 9 of Isu Station (Lines 4 and 7), on the first floor of the Isu Xi mixed-use building where the McDonald's is. Right now the Exit 9 escalator is under construction, so you'll need to come out through a different exit. To think they're only now fixing the flood damage from the Gangnam flooding disaster three years ago... honestly, unbelievable 🙄
The temperature swings have been huge lately. Chilly at dawn, but scorching hot by midday. The waiting seats at Kosi Isu Branch were flooded with sunshine 🌞 — still hot during the day.
📍 Business hours notice
Inside Kosi Isu Branch at 1pm on a weekday, plus parking
Recognized on SBS's "Master of Living" and raved about by actor Kim Seung-soo — a genuine noodle spot ➡️ Kosi is apparently ranked #1 on Naver Place out of 4,490 restaurants in Dongjak-gu! With 1,227 delivery reviews and a 5.0 rating ⭐⭐⭐⭐⭐, the place was still packed even at 1pm on a weekday, past the lunch rush.
📍 Parking info — you can park in basement 2nd or 3rd floor of the Isu Xi complex mall. 1 hour free.
After browsing the whole menu, we ordered the cold udon and mixed tonkatsu.
Kosi's house-made noodle rules
This is the "Kosi's own confidence in house-made noodles" sign posted in the Kosi Isu Branch store. I've copied the brand's own wording exactly.
- Kosi is a healthy meal completed by adding time to good ingredients
- Kosi makes noodles fresh daily from dough aged 48 hours, and any leftover noodles are discarded
- Kosi's broth uses anchovies and kelp sourced directly from the South Sea
- Kosi's soy sauce is imported from Japan and simmered in-house for flavor
- Kosi's tonkatsu is made daily by pounding domestic fresh pork loin, and fried right upon order
Kosi's bukkake udon dough is made with just three ingredients — salt, water, and flour. The dough goes through a first and second fermentation, taking 48 hours to complete. The traditional method of Sanuki, the kingdom of udon!
Do I even need to say how good the kabocha and shrimp tempura were❣️
How were the cold bukkake udon noodles at Kosi Isu Branch?
The tsuyu on Kosi Isu Branch's cold udon (bukkake udon) wasn't too salty, so we kept pouring more and mixing it in.
The noodles were chewy with a springiness like a perfectly tuned string instrument. In Japan, this is what they call having "koshi" (bite/resistance). The dense, sticky chewiness particular to Sanuki udon really stood out. When you bite in, the noodles don't snap easily — you get that firm, chewy resistance all the way through, the textbook style of kneaded, aged fresh noodles~ Absolutely delicious❣️
Mixed tonkatsu with a hefty king shrimp katsu near Isu Station
Whew — the kind of visual you'd expect from a proper tonkatsu place near Isu Station!
The shrimp was genuinely hefty too, fried whole and beautifully.
Look at how evenly the meat inside is cooked. Using a thick cut of pork, biting into the cross-section releases juicy moisture. It chews tenderly with no gamey smell, while the coating keeps the crumbs of batter intact for a pleasantly crunchy bite — the taste of someone who knows what they're doing.
Dipping it in the sauce was so good❣️ Besides the classic tonkatsu sauce, adding a little fresh wasabi or salt really brings out the meat's own clean umami even more~ though I didn't take a photo of the salt-wasabi combo. That contrast in temperature — a bite of cold bukkake udon followed by hot, crispy tonkatsu — was excellent.
What should you order at Kosi Isu Branch?
Once again, a solid tonkatsu spot near Isu Station — KOSHI, Kosi Isu Branch. To maximize that chewy noodle texture, I'd recommend going with bukkake udon (cold udon) over the hot version. Though the hot udon I had in winter was tasty too~
Just the udon on its own might leave you wanting more, so getting the full set that comes with tonkatsu gives much higher satisfaction~ I recommend going with the set❣️
Kosi Isu Branch — 1st floor, units 126 & 127, 300 Sadang-ro, Dongjak-gu, Seoul, South Korea
Where it is
300 Sadang-ro, 1st floor, units 126 & 127, Dongjak-gu, Seoul, South Korea서울특별시 동작구 사당로 300 1층 126호, 127호
