The modern-day manga has its roots in the giga tradition of humorous and satirical pictures dating at least as far back as the Heian Period (794-1185). The genre is perhaps best exemplified by the Choju jinbutsu giga (Caricatures of Humans and Animals), a series of ink-on-paper scrolls from the 12th and 13th centuries peopled with rabbits, monkeys, and frogs engaging in human activities such as wrestling, bathing, and praying. The greatest flowering of giga occurred a few hundred years later when ukiyo-e artists imbued the form with a riot of color and imagination. It is this era that is the focus of Caricatures of the Edo Period: From Toba-style Paintings to Hokusai, Kuniyoshi, and Kyosai, an exhibition comprising some 280 items at the Osaka City Museum of Fine Arts.

The term toba-e, an early type of giga, is derived from the surname of Toba Sojo (1053-1140), who is credited as the creator of the Choju jinbutsu giga. These spare and swiftly drawn cartoons, often published in book format, are immediately recognizable from their small-eyed, flat-nosed, large-mouthed, and spindly-limbed human protagonists. The characters cavort through sparse landscapes, turning routine activities like pruning trees and pounding rice cakes into slapstick. Especially popular in early 18th-century Osaka, toba-e humor turns on visual puns based on well-known phrases and sayings, or sight gags such as men exposing their buttocks and knocking over a crowd of people with powerful farts.

Nichosai (dates of birth and death unknown), an Osaka artist active in the late 18th century, added a more foreboding dimension to giga. His Hell Scrolls, a series of color paintings illustrating dozens of different types of Hell, show gigantic horned devils delighting in the torture of frail gray human beings. Their tools and techniques are associated with the victims' former livelihoods, so the river fishmongers are chopped up, skewered, and broiled over charcoal, the kabuki actors are tied to stakes and force-fed huge daikon radishes (an allusion to the pejorative daikon yakusha, or ham actor), and the soba makers are kneaded, sliced, and grated.

The stars of this show, Katsushika Hokusai (1760-1849), Utagawa Kuniyoshi (1798-1861), and Kawanabe Kyosai (1831-1889), took giga to new heights. Best known for his prints of Mt. Fuji and ocean waves, Hokusai also published 15 volumes of manga, a word that in this case refers to a handbook of sketches rather than an illustrated narrative. These drawings include acrobats transforming their appearance by stretching their eyes and noses with their fingers and pieces of string, and magicians blowing horses and bees out of their mouths or releasing parades of tiny human figures from their kimono sleeves. Hokusai also updated the toba-e genre by fleshing out existing scenes with shading, patterns, and details.

Kuniyoshi was the undoubted master of giga. His anthropomorphized animals, household objects, and toys are so vivid that they come bounding off the gallery wall and into the room. Among his most memorable works is The Small Jewels of Raccoon Dogs (1842), a scene in which yukata-clad tanuki (raccoon dogs), legendary for their huge testicles, cradle their scrotums in their arms or drape them over their heads as a sideshow barker (also a tanuki) entices them with the promise of a true medical anomaly: a small-testicled tanuki. Another print, Cats Enjoying the Evening Cool (1846), shows a grinning male cat extending a muscly paw toward a feline geisha, perched atop a narrow pier in her geta, as he welcomes her aboard his pleasure boat. Scattered throughout the picture are references to cats and fish, including a kimono decorated with a koban (gold coin) motif, evoking the proverb neko ni koban ("money to a cat"), the Japanese equivalent of "pearls before swine."

Kyosai, who studied with Kuniyoshi as a boy and later trained at the Kano painting school, is the only one of the three artists who spanned the Edo and Meiji Periods. Like his predecessors, Kyosai filled his pictures with strange animal and human behaviors, but his ornate style, complex color schemes, and densely packed compositions bring us right up to the manga era. Notably partial to frogs, Kyosai's The Great Battle of the Frogs is one of his finest achievements. The three-paneled print depicts dozens of green-spotted frogs engaging an army of their brown-spotted adversaries in combat across a pond. Clothed in leafy raincoats and skirts, they wield cattail spears, fire sprays of water from the stems of flower cannons, and struggle to reach the opposite shore on rafts made of leaves. Make no mistake, however, these are not the lovable amphibians of the Choju jinbutsu giga -- these frogs mean business, as evidenced by the pools of blood on the ground and the severed heads of their enemies impaled on posts. The 1864 work is thought to allude to the Choshu Expedition, a retaliatory attack carried out by the Tokugawa Shogunate against the Choshu Domain earlier that year.

Such sanguinary episodes notwithstanding, there are few more charming chapters in the history of Japanese art than that of giga, a genre that remains as captivating today as it did when it was first developed centuries ago, and it would be hard to imagine a better introduction to this fantastic world than the current exhibition.