A fixture of The New York Times best seller list - the first volume has spent 48 weeks there -- "Tokyo Ghoul" is more than your standard supernatural battle manga.

A little at a time, creator Sui Ishida draws the reader into a whole new world, with its own biology, its own technology and its own culture. And as in the best manga, he tweaks the rules as he goes along, keeping the story fresh and the reader guessing.

The ghouls of "Tokyo Ghoul" are different from the ones found in folk tales. Old-school ghouls look like monsters, live in graveyards, and dig up corpses or shapeshift into animals to lure the living into lonely places for the kill. Tokyo ghouls, on the other hand, are urban sophisticates who hang out at a local coffeehouse, Anteiku. Even hipster ghouls must eat human flesh to live, however. They can't digest human food, and in fact find it repulsive -- except for coffee, which allows them to find common ground with their human neighbors at Anteiku.

Of necessity, then, ghouls and humans are enemies. The survival of one depends on the death of another -- either the ghouls must eat the humans or the humans must kill the ghouls. So what happens if you have some of each in you?

That brings us to "Tokyo Ghoul's" main character: Nebbishy human Ken Kaneki, a dreamy, bookish guy who receives an organ transplant from a ghoul and is left half-human, half-ghoul - or, as he puts it, "I'd say my soul is human and my body's a ghoul."

Stuck with a ghoul's physical needs but a human's repulsion for fulfilling them, Ken seems to be all alone at first. However, it turns out that Anteiku is run by a particularly enlightened group of ghouls who want to figure out a way to coexist with humans. The manager, the fatherly Mr. Yoshimura, sees Ken as a possible bridge to the human world, and he not only gives him a job but offers to supply him with humanely sourced food. When Ken demurs, Mr. Yoshimura gives him a mysterious sugar cube that can quell his hunger for a little while, but sooner or later, the others warn him, he will have to accept what he is.

Ken's counterpoint is the badass ghoul Touka, who works alongside him as a waitress. If Ken is a human slowly transitioning to ghoulhood, Touka is the opposite: She appears cold and angry at first, but she is also reaching out toward the human world, going to a human school and trying to appear normal to her human friend. Although she feigns a disinterested attitude at times, Touka has a keen sense of justice and not only tries to keep ghouls from taking over each others' hunting grounds but also avenges the deaths of her fellow ghouls. As one expects of a female second lead in a manga like this, she's a hell of a fighter and racks up a number of kills in the first few volumes -- but sometimes she holds back.

Rounding out the beginning of the series are Ken's brash friend Hide, a young man of great enthusiasms and strong intuition; the widow Ryoko, whose husband was killed by ghoul investigators, and her young daughter Hinami; and the stolid Yomo, who takes care of business and watches over Ken and Touka.

The first arc of the series, volumes 1-3, is all about Ken coming to terms with the paradox of needing to eat human flesh to survive while still having human emotions, including not just revulsion for cannibalism but also the desire for friendship and emotional ties. That's not the end of his problems, however: The ghouls have their own predators, the state anti-ghoul squad known as the CCG. Ghouls have no human rights, and the anti-ghoul investigators -- known, ironically, as Doves -- often take sadistic pleasure in killing their prey. The chief ghoul investigators in this arc are the bizarre, almost corpse-like, Mado, who's obsessed with killing ghouls and converting their fighting organs into weapons, and Amon, a strait-laced, dedicated investigator.

They're an odd couple -- Mado is seriously weird, while Amon seems uptight but greatly admires his superior officer. It's almost more chilling, though, to see a cheerful office lady saying, "Ghouls aren't human. They're a threat to us. They deserve to be exterminated." Right from the start, Ishida shows that individuals on both sides can be innocent victims but also can embody pure evil, although most of the characters fall somewhere in between.

"Tokyo Ghoul" isn't a philosophical treatise, however. It's an action manga. The ghouls attack humans and fight over territory; the Doves pursue the ghouls and the ghouls fight back. Ghouls have special organs called "kagune" that spring out of their body when needed; there are different types of kagune that have different powers. The Doves have their own technology: They fashion "quinques," or prosthetic kagune, which they carry around in suitcases and unleash as needed. (The details of this are hinted at in the earlier volumes and are finally explained in Vol. 6, in the chapter titled, appropriately, "Lecture.")

The fourth volume introduces an epicurean ghoul, the Gourmet, with a weird story about a ghoul restaurant that spirals off into craziness. That story arc winds up in Vol. 5, and Ishida picks up with the story of Rize, a voracious ghoul who goes on a killing binge that destabilizes her area of Tokyo. Rize's story leads back to Anteiku in Vol. 6, and at that point the story really starts to expand, with the introduction of a ghoul gang, the Aogiri Tree, and the rollout of a larger conflict.

The original "Tokyo Ghoul" series is complete at 14 volumes, so with the publication of Vol. 7 this month in North America by Viz Media, we're halfway through the series. There are also three light novels focusing on different characters and filling in gaps in the story, and they, like "Tokyo Ghoul," have been licensed by Viz for English release. There are also two spinoff manga, a prequel and a sequel, that have not been licensed yet.

As might be surmised from the subject matter, "Tokyo Ghoul" is often violent and bloody, but there's more to it than ghoul attacks and vendettas. Ishida weaves in surprises, flashes of humor, and some serious human dilemmas as the story unfolds, so it feels like there is always something new just around the corner. Even in the short span of seven volumes, the characters have grown and changed and the world has evolved, but the heart of it remains the universal question of what it means to be human -- and what it means to be a monster.

TOKYO GHOUL © 2011 by Sui Ishida/SHUEISHA Inc.