FOR KEISUKE Suga's third restaurant, he's taken a bit of a risk. Suga, an energetic restaurateur originally from Osaka, recently sold Himawari, a ramen restaurant in San Mateo. and is in the process of selling Hanamaru, a sushi bar in Sunnyvale. His latest venture is Nami Nami, a 2-month-old restaurant on Mountain View's restaurant-jammed Castro Street. It's not your typical Japanese restaurant, at least not in these parts.

Nami Nami (nami means wave in Japanese and is a nod to Suga's passion for surfing) is a kappo-style Japanese restaurant. Kappo is food prepared in the artful, labor-intensive, seasonally driven style associated with the city of Kyoto. It's similar to kaiseki, but less formal and not served in set courses. Kappo food is also known for its use of nontraditional, Western ingredients. It is upscale, bracingly fresh Japanese bar food in which diners watch the chef prepare the food before their eyes. It's like a sushi bar, but the menu is broader and the chef's repertoire greater. Nami Nami has a small bar, but most of the restaurant is given over to tables and chairs, so most diners won't get that one-on-one with the chef.

The restaurant is a risk because, in addition to fluctuating food costs that come from importing pricey, seasonal ingredients from Japan, much of the food is unfamiliar to the typical American diner, even those who enjoy Japanese food. Some of it is going to freak people out. But for diners willing to open their minds and their mouths, Nami Nami offers one of the most exciting restaurant experiences in the Bay Area.

The restaurant seems to have become an immediate hit with the South Bay's Japanese population and visiting Japanese businessmen. On my visits the restaurant was filled with an almost all Japanese clientele. While it must be great to have credibility with Japanese diners, Suga wants his food to be embraced by a wider audience—and it thoroughly deserves to be.

Japanese food like sushi, tempura and teriyaki enjoys wide popularity in the United States among non-Japanese. But if you call yourself a sushi lover and delight in bold flavors and textures like quail eggs, salmon roe and sea urchin, it's time to take things to the next level.

For Nami Nami, Suga hired three Kyoto-trained chefs (one of whom is his cousin) who share cooking duties equally. Two of them have licenses to prepare fugu, blowfish that contains a deadly neurotoxin that can cause instant death in diners if it's not cut properly. (Don't look for fugu on the menu: it's illegal in the United States.) The chefs are young and talented and looking to make a name for themselves, just the kind of people I want cooking for me.

The menu changes every three months with the seasons, and the spring menu debuted last week. The menu is big, maybe too big. There are cold tapas-like dishes, salads, stews, rice dishes, sashimi, noodles, soups, fried foods, grilled dishes and more. My suggestion is to start with a few tapas, salads and sashimi and finish with a stew or a bowl of noodles. Work in a few fried, steamed or grilled dishes if your budget and appetite permit.

For me the cold tapas are some of the best items on the menu. For proof that this isn't another chicken teriyaki and California roll joint, check out the noresore ($8), baby ocean eel served in a ginger-spiked dashi sauce. The shimmering, translucent eels float in a small wine glass above a few shiso leaves as their tiny, metallic eyes peer out. The eels don't have much flavor but their clear, slippery texture combined with the crisp, briny, fresh flavor of the dashi and the bite of the shiso leaf make this an exciting start to your meal.

Iidako, stewed baby octopus ($8), is a little tamer. The octopuses, their bodies no bigger than nickels, are tender and anointed in a salty sweet glaze that complements their meaty flesh.

I also liked the quivering blob of mugwort-flavored tofu ($5). Mugwort is an herbaceous plant that gives the tofu a green hue and an earthy, savory flavor that's enlivened with puréed ginger.

The sashimi is outrageously good. Sashimi for three ($20) included luscious, shimmering slabs of exquisitely fresh tuna, tai snapper and amberjack. On another visit for lunch, the special bento box ($24) included the best squid sashimi I've ever had. It was as fat and creamy as a hunk of Kobe beef fat.

One of the standout dishes that showcased the kitchen's use of non-Japanese ingredients was the amaebi tartar salad ($12). Raw, sweet shrimp are served in a bowl of light and tangy chilled tomato and vegetable soup that tastes a bit like gazpacho. The shrimp (minus the tails) are lightly battered and fried and served on the edge of the bowl. The shrimp are young enough that you can eat the exoskeletons with a satisfying crunch.

The kitchen didn't pull everything off. Green-tea-battered chicken ($9) sounded intriguing and was plenty juicy but the thin crust was bitter and needed a splash of rice wine or lemon juice to wake it up. I was also attracted to the ginjo mushi ($12), sake-steamed clams and Brussels sprouts, a distinctly un-Japanese vegetable. The clams were tender and sweet (although I crunched more than a few grains of sand) but the pairing with the sprouts didn't amount to much.

Given all the menu choices, you may want to forego anguishing over your meal and just utter the magic word omakase and let the chefs decide. But even if you're letting the chefs select your meal, it's OK to give them some direction, i.e., only fish and vegetables.

On my first visit I turned it over to the kitchen, but wasn't pleased with all my selections. While it was the last days of the winter menu and the food was understandably heavier, I was in a lighter, springlike mood and didn't like the abundance of fried and stewed dishes such as the urchin croquette and beef tongue.

Suga is knowledgeable about the food and will help you understand the menu, but the other servers are not so good. Their English is limited and so is their familiarity with the menu. "I don't know" was our server's typical response to our questions. He dutifully got the answers, but all that head scratching becomes tiresome.

You'll probably want to ask a few questions about the special menu category called chinmi. These dishes of salted fish guts, salted sea cucumber eggs, pickled egg yolks and other goodies are designed to go with beer and sake. Kind of like Beer Nuts only different. OK, a lot different. It's advanced eating to be sure, but it can be pretty good. Shuto, salted bonito stomach ($6), sounds gnarly but the glistening little orts were unexpectedly edible and made my sake sweeter and smoother.

Speaking of sake, the restaurant's list of sake and shochu is first-rate. Sake is listed by type (daiginjo, ginjo and junmai) as well as by its relative dryness. Some short descriptions would be helpful, too.

The chefs' creative streak extends to the dessert menu. While there is the obligatory green tea ice cream I was surprised by several other dishes. The yogurt ice cream with berry compote ($7) was fantastically creamy and delicious. And by all means don't miss the rice bavarois ($7), a wonderfully rich rice pudding studded with imported Uonuma rice, Japan's premium grade rice.

Like Suga, Nami Nami's owner, diners at the restaurant may feel like they're taking risks of their own with a menu that will strike some as strange and exotic. But as in life so it goes in food: nothing risked, nothing gained.