Living in, and growing up in the U.S., it's easy to get tricked into thinking that all great literature has come from the States and western Europe (specifically England). While a few non-English speaking writers have made names for themselves in the U.S., (like Nietchze), they're not really high on anyone's reading list. So it sometimes comes as a shock to trip over people like Maurice Leblanc (creator of Arsene Lupin, prototype of the Monkey Punch character Lupin III). Yet, even with Japan's rich history of literature, all anyone really knows about is "The Tale of Genji". (Not including modern-day manga).
One writer well worth reading is Natsume Soseke, who wrote "I am a Cat", a commentary on various people he knew, as well as on just broad character types, in the early 1900's. Soseke is considered a national treasure, and his face was on the 1000 yen note until 2004.
(Ranpo, from the wikipedia entry on him)
However, the person I really want to highlight right now is Edogawa Ranpo, a famed Japanese mystery writer active from 1923 to 1955 (died in 1965). The name "Edogawa" may be familiar to anyone that reads "Meitantei Konan" ("Case Closed") as being the pseudonym Jimmy Kudo uses after being turned into a kid - Conan Edogawa. In that manga, Kogoro Mouri is named after one of Edogawa's detectives, as is the fake name Conan's mother sometimes uses - Fumiyo, Kogoro's wife in the mysteries.
I have to state right now that I haven't read the Edogawa books yet, since I just discovered him from a conversation I had with a friend (and the fact that only two books of his works have been translated to date). But probably the greatest thing about him is his name. Edogawa Ranpo is the pen name for Hirai Tarou. Tarou was a big fan of Maurice LeBlanc, Arthur Conan Doyle and Edgar Allan Poe. And in fact, Tarou took his pen name directly from the Japanese spelling of Poe's name - Edoga Waran Po (Edgar Allan Poe = Edogawa Ranpo). I think that alone is worth reading his works for.