Cold udon restaurant near Isu Station with fist-sized karaage: Kosi

Kosi Isu Branch: a cold udon restaurant right outside Isu Station Exit 9

This time I visited Kosi, a cold udon and tonkatsu place right outside Exit 9 of Isu Station. It's a popular spot known for both its cold udon and tonkatsu.

Walk straight out of Exit 9 and you'll see the Kosi sign and a big lit-up menu board. Alongside cold udon, they have mazesoba-style udon, hot udon, and of course tonkatsu and donburi.

You can also order gara-age and fried shrimp as extra sides. But honestly, even the basic set menus come in generous portions — Kosi never leaves you wanting at this Isu spot.

Inside Kosi Isu Branch — plenty of solo diners late in the evening

The interior is clean and the tables are nice and wide. I visited in the late evening and noticed a lot of solo diners around.

This is the view looking out from inside the restaurant toward the entrance — the kitchen is off to the left. With so many staff on hand, serving and cooking both looked effortless.

It'd be totally fine to come here as a group too.

Cold udon with karaage at Kosi: one piece is the size of a fist

What we ordered was the cold udon served together with gara-age (Japanese-style fried chicken).

The noodles come thick and neatly coiled. Both the noodles and the bowl itself are huge, so the portion is massive. And the gara-age came in four pieces — not the kind of afterthought portion you get as an udon side, but genuinely satisfying enough to order as a standalone dish. I was shocked. One piece was almost the size of my fist!!

On top of that, there's inari sushi (fried tofu pouch rice) too, so there's zero chance of not having enough food. If you want a hearty meal, head to Kosi Isu Branch!

Biting into the sweet-and-tangy fried tofu pouch wrapped around the rice really wakes up your appetite.

The basic side dishes are pickled radish, kkakdugi (diced radish kimchi), and salad.

To show just how big the portion is, I compared it against my fist. The bowl itself is enormous, so don't be fooled by photos of it — you could seriously overeat here, so be careful.

The crispy-fried gara-age was excellent too.

Protein first — now time to pour on the cold udon sauce!

How thick and chewy are Kosi's cold udon noodles?

After mixing the noodles well with the cold udon sauce, it's time to taste them. The noodles were truly chewy and firm. As someone who loves cold udon and has tried plenty of different noodle styles, these rank right up there among my favorites for chewiness. Compared to other places, the noodles here are thicker and firmer, giving them a really satisfying bite. A bite of udon, a spoonful of sauce, then a bite of gara-age — the perfect combo, in the perfect order.

Salad isn't just for the tonkatsu order — even ordering only udon, you still get salad as a complimentary side. So you never feel shortchanged even with just an udon order.

Mixed katsu at Kosi — one king shrimp tempura plus thick-cut tonkatsu

The other dish we ordered was the mixed katsu. It comes with one piece of king shrimp tempura alongside tonkatsu.

I usually worry a tonkatsu order won't be enough food, but at Kosi Isu Branch, even the tonkatsu alone is generous in portion and great in flavor, so there's nothing to worry about.

And to top it off, an appetizing piece of king shrimp tempura — perfect!

It was a huge, crispy fried shrimp — not your average shrimp, but black tiger shrimp-sized. I savored the plump shrimp meat dipped in tartar sauce. Totally satisfied!

You really need something to compare the bowl size to, not just look at the dish alone. This mixed katsu nails both flavor and portion — it just doesn't come across fully in photos.

What sauces come with the tonkatsu at Kosi Isu Branch?

For sauces, you get the standard tonkatsu sauce and tartar sauce.

Tonkatsu can get a bit heavy, so it's a nice touch that they also serve wasabi and salt — pairing them with the pork brings out a totally different flavor from the tonkatsu sauce.

The cutlet is really thick, moist yet crispy — exactly the tonkatsu style I like.

If the thick tonkatsu feels like a lot to get through, a sip of the broth helps. As someone who loves cold udon, I left Kosi in Isu very satisfied. I'd definitely come back!