Why did the Japanese dare not reveal the secrets of the ancient imperial tombs?

Because Japan is a constitutional country, it is afraid to explore the secrets of ancient tombs. It is generally believed that many ancient tombs distributed in Kansai area are the tombs of ancient Japanese royal families. The position of king (emperor) in Japan still exists. Out of respect and courtesy for the royal family, these ancient tombs are managed by the imperial palace office of the Japanese government and will not be excavated.

However, in recent years, due to the need of tomb protection, several ancient tombs have been opened for fixed-point excavation, which is used to protect the river dam restoration technology around the tombs and conduct archaeological exploration.

Simply put, because of the traditional reverence for ancestors, most people are unwilling to be dug up. As for Xu Fudong's theory of crossing the river, it is completely folklore. The ancestors of the Japanese were mainly a mixture of immigrants from the Korean peninsula and the southern islands, which were far from the genes of the Han people in the Central Plains.

* It's no secret that relevant academic papers and conclusions have been published for a long time about Japanese genetic problems. If you are interested, you can look for papers about "East Asian nation" gene or Japanese ancient human gene.