Who was the first emperor of Japan?

According to the ancient historical chronicles, the Kojiki and the Nihon shoki, Japan's first emperor was supposedly Emperor Jimmu, who lived around 660 B.C.
However, this has not been proved to be true: it is widely held that the Kojiki and Nihon shoki based on legend, as both were compiled after the eighth century.
Although it is often said that the tenth emperor, Sujin, was possibly the first historical emperor, it is not until the 33rd empress, Suiko, who reigned from 592 - 628, that actual records can be found.
lt was during this period that Prince Shotoku emerged as the imperial prince.