There was an ongoing public debate on earthquake forecasting in the early 20th century between two Japanese seismologists, Akitsune IMAMURA and Fusakichi OMORI. In 1905 Imamura pointed out in a magazine article that historically Tokyo had been hit by large earthquakes every 100 years on average. Imamura argued that as the last one was 50 years ago, assuming quasi-periodicity, another one could be expected in the next several tens of years. Imamura's thesis was reported sensationally in several newspaper articles in early 1906. Omori responded by making strong criticisms of Imamura's work in a magazine article. The debate flared up in 1912, and simmered in following years. On Sept. 1, 1923 the Great Kantō earthquake occurred, killing approximately 105,000 persons. Some people regarded the occurrence of the 1923 earthquake as proof that Imamura made a successful prediction and that Omori's criticisms were wrong. This episode has lessons for us even today.