Ryu (Tatsu—Dragon), Ko (Tora—Tiger) and Kaku (Tsuru—Crane) are the three most important animals in karate’s early origins from China and Okinawa. In Asai style Shotokan karate, there are other animals referenced for different techniques and their applications (such as the Hebi/Snake, Saru/Monkey, Kuma/Bear and Hyo/Leopard; however, these all originate from RYU KO KAKU.
Furthermore, there are a couple of others points, which I will only briefly touch on today... Firstly, many karada no buki specifically correspond with the type of animal. For example, the boshiken is `RYU`, the hitosashiyubi-ipponken is `KO` and the kakushiken is `KAKU`. Secondly, two of these weapons of the body are not in post-war Shotokan—largely due to the `sportification` of karate; nevertheless, Asai Sensei brought them back.