The karate kata Seisan (十三) literally means '13'. Some people refer to the kata as '13 Hands', '13 Fists', '13 Techniques', '13 Steps' . However, these names have no historical basis.

Seisan is thought to be one of the oldest kata, being quite spread among other Nahate schools. Shito-ryu has its own version and different versions are now practised even in Shuri-te derivatives like Shotokan (called Hangetsu) and in Wado-ryu (called Seishan). Isshin-ryū also adopted this kata. This kata is also practiced in Korean styles such as Tang Soo Do and Soo Bahk Do and is called Sei-Shan or Seishan in Korean. Due to its difficulty, this kata is often reserved for advanced students.

While there are many versions of Seisan in the different Okinawan and Japanese karate schools, the variation we practice at the Mountain River Dojo is that of Uechi-Ryū.

The kata introduces some of the basic techniques such as knee strikes, the one-knuckle punch shōken zuki (小拳突き), spearhand nukite (貫手突き), and the front kick shōmen geri (正面蹴り)

The diagram below is the Goju-Ryu variation of Seisan. Learning this version is also permissible.