The original meaning of this kata is the number 13. The theory is that this originated from the fact that the kata is composed of 13 different kinds of techniques. There is another theory that originated from the fact that 13 is a religious symbol representing strength in Okinawan and Chinese culture. This kata demands the strongest punch and kick. Offense and defense in a super-handgrip is also featured. It also has a lot of secrets too. There are lots of different kata called Sesan in Okinawa and China. It can be said that it is a popular name. http://www.japan-karate.com/