Why is there no question mark in Japanese?

Anyone who knows a little Japanese must know that there is a Hiragana in Japanese ~ its meaning is mostly the modal particle at the end of the question, which is equivalent to "..."? "

In the traditional Japanese thinking, it is believed that this modal particle is used to express doubt, and there is no need to let another punctuation mark express doubt ~ ~

It's as simple as that ~

LS's answer is not very comprehensive ~ there are indeed many young people in Japanese postmodern culture who use question marks ~ but they should not be used with か.

Today's Japanese are not all Japanese before the Meiji era ~ Some traditional old customs are being eliminated one by one ~ ~ This is normal.