Conversation so far:
what does the red dot on the japanese flag mean
The red disc on the flag of Japan represents the sun.
when did the flag of japan with the red disc representing the sun become the national flag of japan
The national flag of Japan, a rectangular white banner bearing a crimson-red disc at its center, was adopted as the national flag on August 13, 1999.

Question: Why were red and white chosen?
Self-contained rewrite: Why were red and white chosen for the flag of Japan?