Kuzan/Aokiji was once an Admiral of the World Government. After he lost in the battle for the Fleet Admiral position he left the marines and wander around on its own. And eventually a shocking news shock the World Government. Kuzan joined forces with
Blackbeard pirates
which is regarded as a traitor to the government when he abuses his position as a Shichibukai.
Question: Why did he joined forces with the pirate group which is a traitor and a threat to the government? Does he not believe in justice anymore in the World Government?