Why are the 500-odd works going on display now? 'There's no particular reason except that it's ready,' says curator Hiroyoshi Tazawa. 'Because we wanted an overview of the whole of Hokusai, it was inevitable that the exhibition would be a big one.'

The exhibition has taken five years of planning. Works are divided into six main sections or periods, marking radical changes in style and genre during a career that spanned some 70 years.

The Shunro, or Study Works Period, concentrates on early apprentice works, executed under Katsukawa Shunsho (1726-1792), and shows Hokusai's growing confidence and the development of the linear fluidity that became an enduring characteristic of his work.

The Sori Period, follows the death of Shunsoh, with Hokusai able to pursue his own interests. He developed an intensely stylised and somewhat idealised view of feminine beauty with a melon seed-shaped oval face that he obsessively explored in works such as Ground Cherry (1801-04) from the series Seven Habits. In this woodblock print, one beauty blows on the fruit of a ground cherry to make a sound, while her companion cleans her teeth, presumably having just done the same.

This almost fetishistic attention to sensuous detail has affinities with the fantasy women of manga and anime. But can Hokusai really be regarded as the first otaku? 'He may not be the first,' says Tazawa. 'But he was definitely an otaku.'

This quality helps explain his frequent forays into new areas and media. Most great ukiyo-e artists tended to concentrate on one or two genres - Toshusai Sharaku, for example, is known for portraits of kabuki actors, and Utagawa Hiroshige is known for his landscapes. But Hokusai embraced many genres, including erotic art, ghost pictures and works depicting plants and animals such as the electric Fighting Cock and Hen (c1827-33).

Each time he became interested in a new style or subject, he would practise drawing it exhaustively, as suggested by Hokusai Manga, his sketchbooks that were published during his life.

'Hokusai was probably an otaku who was interested in many things and became obsessed with anything that interested him,' Tazawa says. 'The variety of his work, after all, has its source in the character of Hokusai himself. Maybe he wanted to show that he could draw and paint anything he wanted in any way he wanted.'

This would seem to explain his ghost pictures, such as the Ghost of Oiwa (c1831-1832) from the series One Hundred Ghost Stories, in which the ghost of the murdered Oiwa is represented as a broken and tattered o-bon lantern, giving the work a surrealist feel.

Towards the end of his life - the Gakyorojin Manji Period - Hokusai turned to religious subjects, as seen in The Priest Kobo Daishi Exorcising the Demon (1844-47). This remarkable work evinces someone stoically settling their spiritual affairs before death.

But probably the main reason people will visit this exhibition is to see Hokusai's best-known series, Thirty-six Views of Mount Fuji (c1830-32), a set of multi-coloured woodblock prints that play with the possibilities of western perspective and sense of space.

'Hokusai was greatly influenced by western art - not only superficially or as a formality,' Tazawa says. 'It was so deep as to convert his vision. He took in the way of seeing things from western art and developed it into Japanese woodblock printing methods. Consequently, as seen in the series Thirty-six Views of Mount Fuji, he achieved landscape pictures that can be characterised by the vastness of spatial representation, with depth and shading.'

Although some in the series, most notably Shower Below the Summit, show the mountain as an object of awe, others seem to mock it, exulting in the ease with which such a towering peak can be trivialised by perspective and distance.

Hokusai's unsettled life reflected the tumultuousness of cities such as Edo (Tokyo). He moved house 93 times and had more than his share of family and financial problems. The latter partly explains why he changed his name so many times.

'He was very badly off,' Tazawa says. 'It's even said that he sold his own name to his apprentices to earn money. Hokusai had other reasons to change his name - often when he tried to transform himself as a painter. He continued to change throughout his life.'

The last name he adopted, before his death at 90, was Gakyo rojin, which means 'old man mad about drawing'.

Hokusai, Tokyo National Museum, 9:30am-5pm (Fri until 8pm), closed Mon. Ends Dec 4