Japan's colonization of Korea -Pan-Asianism

In the reading "Nationalism and Pan-Asianism" I was curious as to Japan's interest in
Korea. As I read, Japan has been interested in Korea since the late 19th century.

Initially, Korea was part of an ancient Chinese Tributary system:
"Trade with us or bow down to us."

Later, Japan's infiltration, and eventual colonization of Korea came about partly due to Korea's
splintered court.
Consequently, Korea's weakened political position probably aided Japan's colonization since
Korea did not present a united front (political or militarily) to combat Japan's
advances.