Sorry! Forgot about Trouble in Tokyo! That's an important part of Teen Titans history!
Anyway, when the Titans get attacked in their home base by a mysterious paint creature, they go to Tokyo to get some answers. For most of the film, they believe that the enemy they seek is a being called Brushogun. But instead, it's the man who captured him, Commander Daizo. Daizo was obsessed with getting fame for his captures. And he did legitimately capture Brushogun, but after seeing his powers, he decided to use him and his abilities to get greater fame and power.
This led him to framing Robin for a "murder", and putting the Titans on the run. In the end though, he got brought to justice.