Before the onion ninja claims me, I'd like to point out something pretty cool.
Sasuke and Kotarou are both names of rather famous shinobi in Japanese History / Legend. Sarutobi Sasuke being the leader of the 10 ninja who served Sanada Nobushige, we know him better as Sanada Yukimura, who served Takeda Shingen during the Sengoku Jidai. Fuuma Kotarou was the leader of the Fuuma Clan during, surprise, surprise, the Sengoku Jidai, the ninja clan served the Hojo Clan and specialized in Horseback Guerilla Warfare and Naval Espionage, Kotarou himself became notorious through his Brigade, a band of 200 or so brigands, pirates, burglars, and thieves who would cause chaos for the opposing army at the most opportune moments. The little sunshine boy's name even uses the same kanji as the ninja's name.
Rain Woman's a fan of ninja it seems.