He is a ninja warrior from Wutai assigned to accompany Yuffie Kisaragi on her mission to infiltrate Midgar, steal the "ultimate materia" from the Shinra Electric Power Company, and restore their homeland's former glory. 
Sonon is a polite, reliable, protective, vengeful, prideful, and forthright man with an overall serious, grounded nature. Despite his seriousness, he has a sense of humor and teases Yuffie throughout their mission. Compared to Yuffie's exuberance, he is far more humble,rational