OK, so manga are hugely popular -- but so are 500 yen umbrellas on a rainy day. Like those cheap plastic parapluies, though, manga seem little more than a temporary feature of daily commuting. Those young furiita and salarymen who thumb through the pages with barely a pause can't be getting much from it -- can they? After all, manga's not art -- is it?

Fusanosuke Natsume would beg to differ. Natsume has been a manga enthusiast since childhood and, as the author of several books on the subject, he was the first to propose that the language of manga has a unique grammar. (Ironically, Natsume, 52, is the grandson of the most well-read novelist in Japan, the late Soseki Natsume -- who appears on the 1,000 yen note.)

In his manga-filled office in central Tokyo, Natsume explains that in manga, the graphics, text balloons, frames and presentation style of the text all convey specific meanings.

Also, he insists, a manga crafted to perfection is one that readers can flip through rapidly with ease. "There was a famous manga editor," says Natsume, "who used a stopwatch to time how long it took to read 35 pages of manga. One manga took four minutes and 35 seconds; he said it had to be under three minutes. But I bet it should be even less than that."

A manga with a superior layout starts the reader's eye at the top right-hand corner of the right-hand page and then leads the eye on a gradual backward-Z course down the right-hand page before propelling it up to the top right-hand corner of the left-hand page.

Natsume, whose name card is in very stylish, hand-written characters, and includes a cartoon face of a bear with its tongue hanging out, is never still for long. He constantly moves around the office to select more photocopies and manga while squiggling on scrap paper with his brush pen to illustrate his theories.

The frames and action in a bad manga layout, Natsume explains, jerk a reader around back and forth between each page and leave him or her searching for the next frame in the sequence.

An unsuccessful layout also fails to set the reader up for the scene, Natsume says, grabbing an example of a manga in which a monster is introduced with a closeup. This one, he points out, makes it hard for the reader to tell where the creature came from, or its position in relation to the main character.

"Who is this guy? Is this girl the same as this other girl? It's all too confusing," exclaims Natsume.

Depicting motion can also separate the amateurs from the artists. "In Japanese manga the place where the event is happening is white," says Natsume. "If a cyborg takes a leap off a skyscraper, the space surrounding her falling body is not filled with the background building, but with white space. This helps the reader focus on the center of the action."

Since manga cannot show every second of the action, "speedlines" and ghost-shadows help show the reader what has happened in between frames.

Natsume explains that although many Western cartoon books have been influenced by Japanese manga artists, they often lack a true understanding of a successful layout. The use of white space and the flow of the layout are both vital elements in conveying the story quickly and clearly to the reader.

Meaning is also conveyed through stylistic choices involving the text and the balloons around the text. Text can be in different fonts to express whether the words are being broadcast from a train station loudspeaker, for example, or being yelled by a sumo wrestler. Similarly, a very light text balloon indicates an inner-thought, while a spiky one may be best to emphasize, say, the mechanical tones of a computerized voice.

For Natsume, the epitome of a good layout is embodied in a frame from a shojyo manga called "Mezon Ikokku (A Moment at the Manor)" published in the 1980s. Here, Rumiko Takahashi, who drew the manga, created a white rectangle across the bottom third of the panel going behind a young man's head, and then -- so it seems -- also showed him from behind in a similar rectangle positioned at the top of the frame. Using this method, a scene that typically would have been depicted in two separate frames is then shown in the same one.

"Even though the pair are facing each other," explains Natsume, "you can see the expression on both their faces -- not the second before the heroine says, 'Please live longer than me,' or the second after she says it, but at that very instant. The camera does not have to cut between them." Natsume is particularly fond of moments like these, where the standard rules are broken without damaging how the story is told.

So is manga art? Some art experts will grant it that distinction, though with certain conditions attached. Ikumi Kaminishi, a professor of art and art history at Boston's Tufts University, comments that "I have a difficult time trying to define [art], especially because its definition changes from culture to culture and period to period. If we accept film and Pop Art as forms of art, manga, too, may be considered as an art form."

Natsume is not so concerned about elusive definitions. "[The term] popular culture does not have a negative nuance in Japan," he says. "Art to the Japanese is something that you hang on a wall in a museum. I don't think most Japanese care about whether manga is art."