Me either, but what the hell, here's a Top 5 list, sorta, of the top selling Japanese books of all times.
Sorry JK Rowling, it's not your stuff... Potter... (say it like you are Malfoy), as... this list is for single-volume books written originally in Japanese. All Japanese names are written surname first. Nice try Rowling JK.
1) 窓ぎわのトットちゃん (Totto-chan—the Little Girl at the Window), by Kuroyanagi Tetsuko. Published in 1981. Sales: 14.36 million (in Japan and China). A children's book, the author is a known Japanese television personality and UNICEF Goodwill Ambassador. Originally published as 窓ぎわのトットちゃん (Madogiwa no Totto-chan), it was an instant bestseller in Japan.
The story revolves around the values of the unconventional education that Kuroyanagi herself received at Tomoe Gakuen, a Tokyo elementary school founded by educator Kobayashi Sosaku during World War II, and it is considered her childhood memoir. I would bet it is something similar to Anne of Green Gables, a Japanese favorite.
2) ノルウェイの森 (Noruwei no Mori; Norwegian Wood), by Murakami Haruki. Published in 1987. Sales: 12 million. Set in Tokyo of the 1960s, this is a story of loss and burgeoning sexuality. It is a first-person perspective of fictional college student Watanabe Toru and his relationships with two women: the beautiful yet emotionally-troubled Naoko, and the outgoing, lively Midori. I'm pretty sure I don't have to read this one, as I lived my own version of this.
3) 人間失格 (Ningen Shikkaku; No Longer Human), by Dazai Osamu. Published in 1948. Sales: 12 million. No Longer Human was initially serialized as a work of fiction in 1948, is narrated in the first person and seems to be partially autobiographical - or at least has themes from his own life, which isn't that surprising because writers write about what they know. No Longer Human is told in the form of notebooks left by one Ōba Yōzō (大庭葉蔵?), a troubled man incapable of revealing his true self to others, and who is instead forced to uphold a fake happy persona.
4) 知価革命 (Knowledge-value Revolution), by Sakaiya Taichi. Published in 1985. Sales: 10 million. Simply put, this book is Sakiya’s non-fictional belief and prediction that a new economic and social value system will come about in the (current) next millennium. He believes that a knowledge-value revolution will unfold as each advanced national faced the flexibility to cope with an utter transformation of its moral standards. Man... the 1980s were just as weird as the 1960s. NO wonder I never had sex in that decade. History of the future...
5) Shōgun by James Clavell. Okay, this isn’t written by a Japanese person, but this 1975 book it is about Japan. And it sold about 15 million copies. The point is, I couldn't find out which book was No. 5... who cares, this book is way more intresting anyhow - I guarantee it... especially considering what No. 4 was. Yeesh. Now... what's Shōgun all about? Well, if you never saw the television mini-series back in the 1970s, let me tell you that the novel was set in feudal Japan just before the Battle of Sekigahara in 1600. The story tells of the rise of the daimyo "Toranaga" (based upon the actual Tokugawa Ieyasu). Toranaga's rise to the position of Shogun is seen through the eyes of the English sailor John Blackthorne, called Anjin ("Pilot") by the Japanese, whose own heroics in the novel are sort of based on the real-life exploits of William Adams. If I was cooler, I could have gotten laid in the 1970s.
And he lived happily ever after in the future that is now his past,