Though I've admired Japanese cinema for years, I'm a latecomer to Japanese literature. Aside from an abiding interest in haiku, I've only recently begun to scratch the surface of what I'm discovering is an immensely rich and distinguished tradition ("Tale of Genji" is considered by some to be the world's first novel, centuries before Chaucer!).
I've kicked off my exploration with some works by pre-war / post-war author Osamu Dazai, for no other reason than that his titles grabbed me (e.g. "No Longer Human", a better translation being "Disqualified from being human"). This was perhaps an odd place to start, since Dazai's small body of fiction chronicles the decay of traditions and, to be sure, some of the personalities and personality types rooted in those traditions. Nonetheless, Dazai strikes me as someone who had an excellent grasp of and ability to convey the world he was losing; hence the reader is treated to a humane and beautiful treatment of traditional forms in decline. Dazai, who died in 1948, seems to have been decades ahead of his contemporaries in cinema; the dissolution he conveys, and the honesty with which he conveys it, prefigures that of the Japanese new wave.
Dazai's works are intensely personal. He seems to spread himself out over several characters in a given novel, and these are dissolute, desperate people (Dazai committed suicide by drowning at the age of 38, having survived numerous prior attempts). His novels don't make for light reading; the economy by which he conveys his images and thoughts is, however, breathtaking.