Jan. 9 (Bloomberg) -- 15 East, a new sushi spot in Manhattan's Union Square district, guarantees an educational experience. I mean that literally -- there's a textbook.

``Tuna has many parts,'' said chef Masato Shimizu after carving a block of pink flesh from the tail of a bluefin. A pregnant woman, sitting across from me at the nine-seat sushi bar, started to smile. She knew what was coming.

The chef passed me an encyclopedia of fish: ``See page 82.''

The book was in Japanese, so I didn't understand much. But the diagrams were pretty.

``Don't keep it,'' the chef later said with a nod and a wink, as he took back the text and passed it to a couple who probably didn't know as much about kampachi -- a type of fish -- as they should have.

15 East, which is in the space that housed Tocqueville before it moved down the block, will soon serve a full menu of modern Japanese food in its 45-seat dining room. That half of the restaurant is run by Marco Moreira, who, with his wife, also owns Tocqueville.

For now, the crowds are mostly sushi groupies. That expectant diner confessed to eating at Jewel Bako ``50 times'' while Shimizu was the chef there. Upon entering, an energetic man approached Shimizu and gave him a high-five of sorts -- with his elbow, to ensure sanitary sashimi.

Cold Fish, Warm Rice

Like Masa or Sasabune, 15 East serves traditional edo-style sushi. Shimizu places cool fish -- sometimes too cool -- over warm rice, brushes on a bit of his secret sauce, then sets the single treat, on a bright-green bamboo leaf, before you. After a few minutes' rest, you are rewarded with another.

But unlike at those other sushi ``temples'' that emphasize rules and order, chef Shimizu's jovial temperament gives 15 East the feel of a friendly neighborhood spot.

``Which one do you like?'' Shimizu gently shouted across the room.

``The one from Santa Barbara,'' a rotund patron replied, after chewing over his two different sea-urchin roes.

Tall, nearly floor-to-ceiling windows provide passers-by a clear view of the Colgate-white kitchen and rusty-red bubinga- wood bar. It's quite a reversal for architect Richard Bloch, who designed the opaque Masa.

Sushi Worship

Similar venues are typically windowless and quietly reverent, better to allow contemplation of sanctified fish.

You may drop by. Half the seats are set aside for walk-ins.

Patrons look like casually dressed West Villagers, in T- shirts, button-downs and cashmere sweaters. Eclectic classical and jazz play over the din of complete strangers chatting.

You may construct your meal by the piece at 15 East, but on Thursday every patron ordered an omakase -- a chef's choice of sushi or sashimi ($55), or of both ($75).

A $120 chef's tasting menu is for those who also want to sample some of the kitchen's incipient warm dishes, such as braised tilefish with onion broth.

My dinner for one, which included the $75 omakase, an extra flight of sushi, two glasses of sake and dessert, cost $131.

15 East is at 15 E. 15th St., between Fifth Avenue and Union Square West. Information: +1-212-647-0015.

Pricier Per Se

Thomas Keller's Per Se, one of the most expensive restaurants in Manhattan, now charges its patrons even more -- nearly one-fifth more.

Dinner for two, with wine pairings and the ``optional'' foie gras, can easily cost $900.

Starting tomorrow, you will have to hand over $250 for either a nine-course chef's menu or the tasting of vegetables. Those options used to cost $210.

Don't worry, service is included, so no need to tip.

When I dined at Per Se about two years ago, the tasting menu was $150 and the vegetarian option was only $135 -- service wasn't included back then. After tax and tip, our almost four- hour experience, which included foie gras and wine, cost $700 for two -- a relative bargain.

Does this mean the 64-seat venue will have to work harder to fill its books? I doubt it; Per Se has had a two-month wait for reservations since it opened in 2004, in spite of the price hikes.

But as the cost of New York City dining moves further into the stratosphere, it's likely that average gourmands -- those without corporate accounts who indulge in the occasional splurge -- will occupy fewer seats in this exclusive eatery. How sad.

Del Posto

To be fair, Per Se isn't the only fancy restaurant to jack up its prices. Mario Batali's Del Posto recently raised its tasting menu to $175 from $120, while the cost of a wine pairing nearly doubled, to $125 from $65 per person.

So much for a post-Christmas sale.

Per Se is at Time Warner Center, 10 Columbus Circle. Information: +1-212-823-9335 or http://www.perseny.com. Del Posto is at 85 Tenth Ave., near 16th Street. Information: +1-212-497-8090 or http://www.delposto.com.

(Ryan Sutton is a writer for Bloomberg News. The opinions expressed are his own.)

To contact the writer of this story: Ryan Sutton in New York at rsutton1@bloomberg.net.

Last Updated: January 9, 2007 00:03 EST