Sushi Koshu

We had live Ayu fresh river fish from Japan as well as live surf clam, toro, udon, uni etc. it’s always fresh and delicious

Not a bad meal here! We had a work lunch here so we got a lot of different things. The portions were very good and not too heavy.
Here is what I had:
1) Beef Teriyaki and Sashimi combo — The beef was yummy and the sashimi was so fresh adn thick cut. It was almost like a steak and was very good quality. The combo came with rice, potato salad, and pickled cucumber/​seaweed/​shrimp.
2) Fried Ice Cream — We got green bean and red bean flavors. It was good but the outside dough was not crunchy like fried ice cream usually is. It was more like bready, but it was a good dessert.
The customer service was excellent, the décor was beautiful, and I was very impressed. Most restaurants around here do not bother making the menu easy to navigate but I was happy with how easy it was here!

I’ve been to so many Japanese restaurants and I think this one is very authentic one. The sushi chef is an Japanese craftsman, he made really great sushi. Highly recommend the BLACK COD sushi, it’s not showing on the sushi menu but you can ask for it. Many sushi chefs at other restaurants are Chinese or Korean, I can’t say they are not good enough but this Japanese chef really played differently with sushi.

The food was alright. Everything was fine except the waitress. Im not sure if shes Japanese but she was speaking chinese to us. The russian roulette roll was supposed to have one spicy roll in it but it didnt. That wasnt a big problem but we let the waitress know. She simply said it should have had a spicy roll in it and didnt advise to help or ask the chef.

Never been so pissed. Here first and didn’t get talked to or served for half an hour and just decided to leave. Other people got service. In fact a waitress talked to a couple for a half an hour then another waitress talked to the same couple. The first waitress instead of talking to me decided to do paperwork and the guy working was walking aimlessly. Never again.

I have been a regular for this place for the past 4 years and I have been fighting the idea to review this on Unilocal because I just don’t want more people to find out this treasure. But I feel I really own them one.
So if you are a parent with toddler (s) but still want to enjoy a good sushi bar experience; this is the place you are looking for. Ever since my kid was able to sit up, we brought him to the bar and he always gets his very special service. The father and son sushi chefs are very patience with their little customers; therefore, parents can enjoy a peaceful dinner.
They only serve seafood which is in season, so just let them serve you omakase and of cause don’t forget to get a drink with you chef.

Very, very disappointed. This is one of the few sushi places with good reviews around my area. I had pretty high expectations, which were sadly not met.
I ordered their chirashi bowl and the boyfriend ordered one of their rice bowls. The fish in the chirashi bowl was far from fresh and had a really bad fishy smell. My boyfriend’s rice bowl was mediocre. The meat was very dry despite being doused in sauce.
Their hot tea is made from powder as well. Overall not impressed and don’t see myself coming back :/

4÷5− Can’t resist rounding up when it comes to a solid chirashi
I’ve been dying to try this place since it opened but I never have time so I finally decided to just suck it up and get a meal to go and I really loved it. The main down side to this place I’ve seen is that their service can be slow. They’re very nice just not always on top of everyone that’s coming in and out. Even with so many servers, there were customers who walked in who weren’t helped for a good few minutes. However, I adore their deluxe chirashi so much I would not hesitate to put up with some slightly slower service to get it again.
The deluxe chirashi + chawanmushi + miso + salad was $ 35. The miso was piping hot when I got to it which I appreciate since with takeout I often end up with lukewarm soup. The taste of the seaweed they use really comes out and it has a slightly different taste from miso soups from your average sushi restaurant. It’s almost cleaner tasting. I skipped on the salad because it looked average and I’m an awful person who doesn’t eat her veggies. The chawanmushi was typical (aka delicious because who doesn’t love steamed egg) and I was fine with that. The deluxe chirashi is definitely the highlight. They really cram the bowl full but they also kept a beautiful presentation. I love Akasaka when I need bang for my buck and I’m willing to sacrifice some quality but the chirashi here is both reasonably priced for the selection and the quality is exceedingly better than Akasaka (I’d say better than a lot of «$$» sushi spots in fact). The rice itself is a bit disappointing though. It’s not very well flavored at all.
For my chirashi I got the following (I tried to remember as much as I could but these are just what I could recall/​figure out– didn’t ask the waitress since I got takeout):
–2 pieces of tamago (decently well made, flavor wasn’t quite right)
–1 piece of kamaboko (fishcake) (looked pretty? not sure why it was in here besides for looks)
–Several smaller scraps of uni (not the best quality but not the worst. has that slightly bitter taste with a bit too much «ocean» but it’s not awful either)
–1 piece of ika (great quality, slightest bite but extremely smooth)
–2 pieces of toro (somewhat fatty, not fully melt in your mouth but decent)
–2 pieces of salmon (surprisingly fatty and rich)
–2 pieces of hotaru ika (stuffed with some spice. I believe it was some sort of chili paste with yuzu)
–1 piece of a «roll» made of sweet pickled daikon with various pieces of fish inside (first time having the combination, the sweetness takes over quite a bit but it was nice to have one piece of something slightly brighter)
–Small pile of ikura (pretty good quality, it had that clean «pop» that I love)
−3−4 pieces of various white/​silver fish (I am really bad at telling white/​silver fish apart. I also lost count… I think one type was aji and one type was some species of yellowtail– possibly hiramasa?)
–1 piece of amaebi topped with (what I’m guessing) is pickled wasabi and yuzu w/​head & lemon packed separately (creamy, fresh, and sweet and I loved the extra bit of flavor they added. The head wasn’t quite as well fried as I like)
–1 piece of akagai (normal quality, not too chewy_​
Overall, it was a great meal. If I received the same quality of fish for a more expensive sashimi platter I may be less happy but for this price and variety, I was extremely satisfied. I would love to come back to try some of their other items.

This place was formerly called Jubei!
I came here with a friend for a quick dinner & some sake.
We ordered the Large Sashimi, Jalapeño Seared Yellowtail Sashimi & a Large Hot Sake.
The fish was fresh, thick, & juicy! I’m so glad there’s a good sushi place in Diamond Bar.
The service was good. But when we asked for the check, the server forgot about it because she was just standing in the back kitchen. then the hostess stand then proceeded to run food to another table. I reminded her again… andddd she forgot again. haha But eventually another server brought it over.
I strongly suggest trying this place out!

THIS PLACE. so good. quality fish, great tasting food.
Premium chirashi bowl (toro included!) is worth the price tag. SOOO much better than Akasaka’s chirashi bowl! Why? Higher quality fish, cleaner presentation; just all-​around more classy. I usually find a friend to split the premium chirashi bowl with and if I’m really famish, we’ll order a side. I can’t go back to Akasaka now, whose chirashi bowl looks like a beefheaded poser compared to that of Sushi Koshu’s.
Lunch is very reasonable here; a good variety combo/​bento box choices, as well as rice bowls (sukiyaki bowl is tasty, all warm and comforting…) Many meals will come with sides like salad and/​or a savory pot of steamed egg with mushrooms.
Legit Japanese, the menu isn’t dominated by weird Americanized rolls. We adore this place, and come as often as our wallets allow.
(the –1 star is for one of the waitresses who we ALWAYS seem to get stuck with and who isn’t very nice. She’s not mean, and maybe it’s just stress + RBF/​angry resting face… but it’s off-​putting to our otherwise perfect experience.)

I recently made my first visit to Sushi Koshu for a Friday dinner with the family. My sister suggested this place because she had very positive experiences here with her husband and sons. I arrived right at 5 pm when it opens for dinner service. I was pleased to discover that 5 pm-​7 pm, from Tuesday — Friday, is happy hour. The menu consists of a handful items from their regular menu at a great deal for $ 5 each. In order to be able to order from the happy hour menu, at least one person in your party must order an alcoholic beverage.
HAPPY HOUR MENU:
We ordered 3 of the spicy salmon crackers. Each order consisted of 4 thin «crackers» (thin layer of rice between two sheets of flavorful seaweed, fried and crispy) topped with spicy salmon, a sliced avocado, and drizzled with both eel sauce and Japanese mayo. Every bite was so tasty and balanced, and I really appreciated the fact that the crackers weren’t doused with the sauces, which some restaurants do with their sushi sauces.
We also ordered fried chicken wings for my nephews, which they devoured happily, as well as a good-​sized salmon skin cut roll, which was slightly salty but still good.
DINNER MENU:
My dad ordered the Take Sushi Platter, which had 10 pieces of sushi and a spicy tuna cut roll. The sushi, prepared with fresh cuts of fish, was presented attractively on a long platter. My dad enjoyed it very much.
My nephews (5 and 2 yrs old) shared a kids beef teriyaki combination served on a space shuttle platter, which included vegetable and shrimp tempura, potato salad, california rolls, a bowl of rice, and a calpico drink. I was impressed with the size, variety, and taste of their food.
We also shared a sashimi platter. We loved the delicious cuts of fresh fish. I savored each bite.
SERVICE:
The hostess/​waitress and other staff were all so nice and interacted with my nephews in such a positive way throughout the dinner. They also brought them each complimentary ice cream. I would give them 5+ stars for the service, but have to dock a star for never giving us our order of fried calamari from the happy hour menu and initially not giving us our 3 orders of spicy salmon crackers (They only gave us one, and we had to tell them that we had not received our other two.)
Overall, it was a great dinner, and I definitely plan to return.

I’ve been here twice and the fish tasted off the second time I came here. It wasn’t that the fish tasted spoiled. The color and texture of the sushi seemed ok. It tasted as if the chefs didn’t clean or wipe down their knives and cutting board. Some pieces (salmon, shrimp) tasted ok and some had a disgusting bitter, dirty, fishy taste/​smell (especially the tri-​fish cucumber wheel). It was the kind of taste/​smell combo that happens when it tastes so bad you can smell it after you ate it.
This is a real shame because the first time I came here the fish was fine. I’m guessing the sushi chef on my second visit was either new or sloppy. If you look at the pictures I posted there are some dark spots on the sashimi where parts of the skin were left on. This type of careless preparation leaves me apprehensive as to what else might have been looked over during the preparation of the food.
Two stars only because my experience could have been the exception and the service was decent.

Came here with high expectations on a recommendation. We sat the bar but the service time for the food was actually pretty slow. The fish was just average. It wasn’t exceptional but it wasn’t bad either.

Sit at the sushi bar, let the chefs do the ordering for you, and you won’t be disappointed. It’ll cost a pretty penny but it will be one delicious meal. The sushi quality is great and Brent and Tommy San never cease to amaze us with the different kinds of fish and preparation. One of our favorites is the torched black cod. So. Good.
Ps. They just recently started offering happy hour too

Went here today with 3 friends.
We ordered Ankimo (Monkfish Liver) $ 7 for a starter and my friend and I split the Deluxe Bowl ($ 35) with Chawanmushi.
This restaurant was so delicious, that we actually spent some time AT THE RESTAURANT discussing how we’ll miss it when we leave (noting that this was the first and only time any of us have been there).
The fish in the Deluxe Bowl was super fresh; simple but extremely tasty. We totally also didn’t know you could eat the fried shrimp head, so extreme FOMO in leaving that little guy in the bowl:

The bowl was enough for both of us to share.
The Ankimo was super savory. They’re gross-​looking fish, but dang, do they produce a tasty liver.
We’ll be back!

So, BF has been hankering to come to Sushi Koshu for their omakase since he stumbled upon this place a few months ago.
When’s the best time for an omakase? Birthdays? Anniversary? Saturday? Monday? Yes to all the above. There’s never a bad time for sushi and omakase.
The first time we came here, we had the chirashi bowl, since **cough, cough** we had a lamer that doesn’t branch out in her taste of sushi, so we kept it safe — sitting at a table, rather than at the bar, and ordering. WE had the deluxe chirashi bowl — standard fare, tuna, toro, salmon, uni, egg, tamago, ikura, halibut and so forth. It came with the steamed egg, salad, and miso soup. All for $ 30. Not too shabby. Good portion sized, fresh fish, can’t complain.
However, this time, we came for the omakase without the lamer. Also had to wait a short while for the sushi bar. AND I can’t stress hard enough, please sit at the bar. You get the best experience there. You engage with your chef — Brent. You see what you’re about to eat. You ask questions, you talk, you have fun. And then ideas for the next visit to Sushi Koshu.
For the omakase, there’s 3 price points (40, 60, 80). We got the $ 60 omakase. It was affordable and because it was for my birthday, it might have been a little bit more special: D. Thank you Sushi Koshu. It was nice that there’s no set menu for the omakase, you get what Mr. Brent chooses and decides you get!
What was on our omakase:
Starter, sesame oil noodle and turnip salad.
Monk fish, seaweed, and cucumber salad.
Oysters two ways: one with uni and homemade ikura (kumamoto oyster, i believe), and one with a radish and masago (Pacific Oyster)
Halibut
Red Snapper
Miso Cod (cooked) OMG!!! It was so tender, moist, deliciously marinated
Sweet Shrimp
Amberjack
Yellowtail belly
Steamed Egg
Ikura
Seared Scallop and Uni (OMG!) BEST ever. If you can get a taste of this… it’s most amazing flavors ever.
Rock Shrimp handroll — rather than blue crab. Special for us **wink**
and we included toro onto our omakase. Btw, we told Brent we’d had it seared, raw… and because he is a genius (!), he seared our toro and flash marinated it. It is some voodoo magic. because that toro was AMAZING. i can’t describe how amazing that food was.
Thank you Chef Brent, you made my birthday an unforgettable one. AND of course, thank you BF for paying for it.
Location: Hard to find, strip mall with other restaurant. Across the street from Paper pot.
Parking: plenty.
Price: Reasonable.

Slave girl just gained another year of life experience since birth and to celebrate her wisdom improvement, a night of celebration is indeed required. I have always wanted to try omakase at Sushi Koshu since I talked to Brent, what’s a better time than this?
We got $ 60 omakase as suggested. It was affordable and usually we get to try most of what they have to offer for the day. What I really like about their omakase, unlike some other places, is they don’t have a list of what you will get. Then again, omakase with a list is not really omakase right? The food we got was fresh and creative. Brent was very knowledgeable about his food and very easy to talk to. He made the whole experience fun and delightful. The service was spot on and I have never had bad experiences with this restaurant.
I would strongly recommend their omakase if you haven’t had it yet at this awesome place.

We came here for a family gathering on a random Sunday. We were visiting a relative in the area and they suggested this restaurant that they come to regularly.
They do have lunch specials and it seemed like the chirashi was the most popular. It really did look great and my brother who is a fan of the dish thought it was pretty decent for the price. I don’t know what hit me but I ordered the eel box and it was pretty tasty too.
Mom got the amberjack/​kanpachi collar lunch special. They gave her a monster portion because I guess the fish that day was huge. She said it was nice and fresh, delicious and finished the whole thing.
Service was great, very attentive and quick to refill and clear the table. In all fairness, I can’t say this is what everyone gets because the relative we visited is a regular here and seemed to be pretty chummy with the lady helping us. The restaurant, however, wasn’t very busy.
Nice meal with nice people we hadn’t seen in a while. Not something we’d go out of our way to eat but no complaints!

Simply Divine.
Dinner choices was simple yesterday: Good Sushi. After a long absence of Sushi Koshu, my husband and I decide to revisit this place again. We have totally forgotten how good this place was!
Upon arrival, we requested the sushi bar and got seated immediately. We decided to do the omakase $ 60 per person and was anticipating some yummy delights. The chef asked before we got started what we like and dislike. Each dish came out to be appetizing and flavorful. Loved all the stuff that was served to us. With me requesting no onion in my food, I did not see a tiny green speckle of onion in my plates. I was very pleased.
We were so glad we chose to eat here. Would definitely come back again and would do it sooner.

MY ULTIMATE FAVORITE PLACE FOR SUSHI! OMAKASE! :)
Food:
Amazing Omakase! Simply amazing! Their food here is really fresh and good quality! I like how its sorta not that traditional. There’s a lot of thought process put behind each dish the chef creates! Their white fish here is very yummy! Oh and we had uni that day too, they kill it live! I think we had mackerel or somthing type of sashimi, I guess that was killed live too! You’ll see in my pictures! Honestly, I don’t remember what we had or what’s it called but it was super yummy LOL.
While I was eating, I was talking to the couple next to me and they told me they have been with them the chefs for about 13+ years of eating sushi! That’s pretty amazing! You know food has to be ridiculously good to follow them to another location and stick with them that long!
Oh side note, so I came here once for chriashi bowl; 2 separate times, one time for deluxe and another for regular. They regular is so not worth it sorta mediocre. However the deluxe was very good! You get so much variety!
Service:
This restaurant is owned by 2 chefs who are father (Tommy San) and son (Brent San)! The chefs service are spot on!
Price: I think the Omakase ranges from $ 65 and up! It’s reasonably priced for the amount of food and quality you get! We got 2 orders of their kobe beef nigiri so our bill was sorta pricey! Why you asked 2 orders? Its because I forgot to take a picture –_​_​– I was like oh no I have to post it on Unilocal!LOL
But it really depends how much you eat or order, so the price really fluctuates! It’s kinda hard to give a set price cause it all depends on what the chef makes you.
Location: Easy to find. Knew about this place without Unilocal lol, but decided to come cause there were decent reivews! Lots of parking. Its located in a korean ish plaza.
Conclusion: Definitely coming back its delish here! So fresh!