It is commonly believed by traditional Shorin Ryu practioners that the Seisan or “13 hands” kata was created by Yonamine Chiru as a means of protecting her baby on her back during a fight. The positioning of the karateka’s body in relation to the imagined opponent is such that the back is kept away from the opponent. This is exhibited by the fact that each transition from move to move is performed in a “half moon or crescent moon’ shape when move from stance to stance.

Shotokan founder Gichin Funakoshi, who originally studied Shorin Ryu under Yasutsune Azato and Yasutsune Itosu, renamed the kata Hangetsu or “crescent moon”, because of the arc-shaped steps found in the form.