Alternative kanji: 抜砦. Also known as Passai.

Literally, Bassai means "to extract and block off," but it is usually translated as "to penetrate a fortress" or "to storm a fortress."

Bassai was Funakoshi Gichin's substitution for the Okinawan name of the kata, Passai. It is thought that the version, Matsumura no Passai, named after the legendary Mastumura Sokon evolved into Oyadomari no Passai, named after Tomari-te master Oyadomari Kokan, and then to the version taught by Itosu Anko, Funakoshi's sensei. That version became Shotokan's Bassai Dai, while a variation created by Itosu was carried on as Bassai Sho.

The origin of the kata, like most, is obscure. One theory is that it is related to leopard and lion forms of Chinese kung fu. Another is that it is related to Wuxing Quan (Five Element Fist) kung fu.

The Shorin ryu version, which resembles Oyadomari no Passai, is much softer than the Shotokan.