MOSCOW — Grigory Chkhartishvili, the best-selling Russian writer known for his detective novels set in imperial Russia (written under the name Boris Akunin), and for his foray into opposition politics directed against Vladimir V. Putin announced that from now on he would devote himself to writing a multivolume history of Russia.

“Some writers dream of becoming the new Tolstoy, others the new Chekhov,” he wrote on his blog on Wednesday. “It’s come time to acknowledge that I have always dreamt of becoming the new Karamzin,” he said, referring to Nikolai Karamzin, who wrote an early-19th-century 12-volume “History of the Russian State.” “I am no longer a crime novelist,” he declared....