“Their cellphone bills were easily reaching $1,000, so many people experienced what they called ‘packet death,’ and you wouldn’t hear from them for a while,” said Shigeru Matsushima, an editor who oversees the book uploading site at Starts Publishing, a leader in republishing cellphone novels.

The affordability of cellphones coincided with the coming of age of a generation of Japanese for whom cellphones, more than personal computers, had been an integral part of their lives since junior high school. So they read the novels on their cellphones, even though the same Web sites were also accessible by computer. They punched out text messages with their thumbs with blinding speed, and used expressions and emoticons, like smilies and musical notes, whose nuances were lost on anyone over the age of 25.

“It’s not that they had a desire to write and that the cellphone happened to be there,” said Chiaki Ishihara, an expert in Japanese literature at Waseda University who has studied cellphone novels. “Instead, in the course of exchanging e-mail, this tool called the cellphone instilled in them a desire to write.”

Indeed, many cellphone novelists had never written fiction before, and many of their readers had never read novels before, according to publishers.

The writers are not paid for their work online, no many how many millions of times it is viewed. The payoff, if any, comes when the novels are reproduced and sold as traditional books. Readers have free access to the Web sites that carry the novels, or pay at most $1 to $2 a month, but the sites make most of their money from advertising.

Critics say the novels owe a lot to a genre devoured by the young: comic books. In cellphone novels, characters tend to be undeveloped and descriptions thin, while paragraphs are often fragments and consist of dialogue.