Her poetic, street-wise writing stood out so starkly among Internet diaries in Japan - which, like those around the world, tend to be more informative or gossipy than narrative - that she is now Japan's biggest literary star.
The 31-year-old won this year's Akutagawa Award - named for "Rashomon" author Ryunosuke Akutagawa - which is Japan's most prestigious honour for a new writer.
There are more blog posts in Japanese than any other language, according to Technorati, which tracks nearly 113 million blogs globally. Last year, Technorati found 37 percent of all postings were in Japanese - about 1.5 million per day. Postings in English - from Americans, Britons, Australians and people in many other countries - accounted for 36 percent of the total.
Kawakami is unusual in the extent of her success. But Steve Weber, an American who has written about marketing books online, said Japanese writers are far ahead of Americans in making their work available on the Internet. Many have had successful books published after producing novels intended to be read on mobile phones, for example.
In the US, publishers are just starting to understand the market power that writers with hit blogs can wield, Weber said.
"Popular bloggers are definitely being targeted by smart publishers because the publishers realise that the authors have already done the hard work of book marketing," he said in an email from Falls Church, "They've attracted the audience."
US bloggers who have been picked up by major publishers include Julie Powell, author of "Julie and Julia: 365 Days, 524 Recipes, 1 Tiny Apartment Kitchen," which chronicles attempts at Julia Child's classic recipes, and Colby Buzzell, a US soldier in Iraq, who wrote "My War: Killing Time in Iraq."
Joichi Ito, Internet entrepreneur and Technorati board member, says Japanese tend to view blogs more as exchanges with friends and a personal outlet than as news sources as Americans do, for discussing politics, technology and other issues.
"More content in Japan is personal, and more content in the US is media-like," he said.
Kawakami's readership has shot up from a handful of people when she started the blog in 2003, to about 10 000 a day, soaring to 200 000 on January 16, the day she won the Akutagawa. She writes in frenzied, urgent prose that gurgles with furor.
"At first, the blog was the only place I had for my writing," she said, confident in her gaze, despite looking frail in a mini-dress. "You know how many people are accessing it, and so you know right away when you've written something that's drawing interest."
She started the blog to draw attention to her music, but the early entries became her first book. Her third book won the Akutagawa.
Despite her newly found fame, Kawakami - an admirer of American writers J.D. Salinger, Kurt Vonnegut and Jhumpa Lahiri - must still fight criticism from conservatives.
Shintaro Ishihara, the right-leaning governor of Tokyo, who won the Akutagawa in 1955 and sits on the awards committee, has lashed out at Kawakami's selection.
"The egocentric, self-absorbed rambling of the work is unpleasant and intolerable," he wrote in the magazine Bungeishunju, which administers the Akutagawa.
For the most part, however, Kawakami's voice is winning accolades for exploiting the drawling dialect of Osaka, the western city where she grew up, which is emerging as the hip language of modern-day Japan - the language of the standup comics and vernacular slang.
Adding to the appeal, Kawakami's award-winning novella, "The Breast and the Egg," explores the ideas of divorce, the questioning of beauty standards and other themes of solitary womanhood that are still relatively new territory in Japanese literature. Kawakami's stories in some ways are those of Japan's Everywoman.
For now, she said, she wants to stay away from stories of relationships with men and sexuality that characterised past Japanese female writing.
"It's about living, our body, the changes of the heart that accompany the body, the urgency, the problems being born, moment by moment," Kawakami said. "The fact that we are always doing our best at living."
On the Net:
Kawakami's blog: http://www.mieko.jp/