Even though you have been hit by a tsunami of information about Chris Lucas' new Japanese layer cake on Flinders Lane (the glamour! The Chablis bar! The legitimate Korean and Japanese chefs!) you arrive oddly unprepared for the restaurant itself.

Much of what you have heard about the lofty ambitions of this sibling to Chin Chin, Hawker Hall and Kong relates more to the premium top floor, Kuro Kisume. Opening next month, this might be considered the Amex Black level, comprising curtained private tables, a 12-seat bar for $175 kaiseki menus and browsable racks of Grange. Already operational up here is the Chablis bar, where tables are as gold as the hyper-specific wines and artistic Japanese bondage pics from Nobuyoshi Araki.

Today, we're here for the Kisume of the people, spread across the two lower floors. These tiers still represent a jump in style for the Lucas Group. The entry-level sushi bar glows, and custom velvet chairs envelop you. The room is at once luxe and energetic and high-profile sommelier Jonathan Ross (ex-Eleven Madison Park) is there for all your Chablis, sencha tea and daiginjo sake needs. But in some ways it's a little more Lost in Translation than Jiro Dreams of Sushi.

Your dining experience can be night and day depending on how you order.

Go a la carte and you are presented with two menus: hot dishes and a placemat menu of sushi that works good fish – and it is quality Australian and New Zealand tuna, mackerel and uni, some of which is kept alive at a Moorabbin warehouse – into either beautiful clean sashimi (great) but also multi-colour battleship and green rolls, or overly compact "golf balls" made by twisting the fish and rice in cling film, some of which is blinged up with gold leaf.

Is that an issue? Not really. Disco sushi has a place. But if you heard Lucas's talk of not importing anything from Tokyo and having cornered Australia's fresh wasabi market and thought Kisume would walk a purist Minamishima or Kenzan line, best adjust your expectations before ordering the deluxe box.

Sure, it's a relief to not have to read the overwhelming menu, arranged by vague names instead of by fish, but the chopped spicy tuna loaded onto cucumber rounds, flame-licked wagyu nigiri and even the Alaskan king crab rolls wrapped in soy paper (supposedly to allow the crab to shine, although too much wasabi kills that notion) feels a little more entry level. Especially when it comes with soy sauce in a spray bottle.

On the other hand, an $88 omakase progression of eight to 10 nigiri, now available if you nab a seat at the bar, reveals Kisume's potential. A black plate appears on the counter and head chef K. S. Moon presents bluefin tuna belly, meltingly soft over just-warm, nutty rice. There follows ruby backstrap, kingfish belly, infinitesimally crosshatched, and sticky strips of calamari sparkling with orbs of salmon roe.

Each piece is enhanced with judicious notches of ginger or shiso leaf paste, maybe a creamy dab of uni, or daikon citrified by yuzu. To follow, a savoury bowl of miso washes around house-made silken tofu shredded like a pom pom with a few chrysanthemum petals at its heart.

Kisume can certainly play with the big boys if it wants. But it also sometimes gilds the lily and sprinkles it with diamantes for good measure.

Crisp wagyu truffles, with truffled mayo, are meatballs with mozzarella hearts that remind you of a burger. The minced tuna belly tartare, capped with yam, mountain peach, tapioca and shiso, ringed by a soy moat, is stunning but busy and so chill in its ice bed it zaps the core flavour of the fish. Potstickers, instead of being laced together, are joined by a base as thick as a brandy snap, making the dish greasy.

On the flip side, I love a dish of mackerel, spliced and grilled, its natural oils countered by chilli and sesame ponzu and back notes of ginger. So, too, the supple steamed dumplings filled with crab crowned with a quail egg yolk.

Intensely refreshing soba noodles, chilled and washing in a dashi broth beneath a battle shield of sliced lime is needed to counteract just the sight of fillet steak burdened by a thick tile of foie gras.

The take-home message here is that Kisume is as crowd-savvy as any of Lucas' restaurants. It is a beautiful, buzzy, busy, well-serviced piece of Melbourne's Japanese landscape. But it's more party than pure; more mainstream than Minimishima. Purists: go omakase or wait for Kuro.