Later, Buddhism spread to the East, so it was required, but it was in conflict with China culture. In China culture, the body and skin are influenced by parents, but the Buddhist system requires tonsure. Buddhism also claims that parents are Fukuda, and they should be the most grateful to all beings. Therefore, as a reconciliation between the two, you must shave your hair when you become a monk to show your gratitude to your parents. There is no need to shave your beard.