Sōchin (壯鎭) (Japanese: "Tranquil Force") is composed of two characters: “SO” and “CHIN”. Most people mispronounce the name of the kata by saying the last syllable as if it were chin - like the chin on your face. This character should be pronounced cheen, not chin.
“So” can be interpreted as robust, manhood, ancient peace, energetic, vigorous or grand. "Chin" can mean suppress, put down by force, or to make calm, then Sochin would also mean “Grand Suppression”, "Energetic Calm”.
“Sōchin” is a kata practiced in several styles of karate. It was taught in the "Naha-te" school in Okinawa by Seisho Arakaki also Kenzo Mabuni (Shito-Ryu) apparently reported that his father learned this kata from Higaonna Kanryo, his instructor of the Naha style of karate (Goju-Ryu) and in Shotokan called Hakko (“Eight Storms”) for a while.
Funakoshi originally tried to rename this kata from its Okinawan name of "Sochin" to a Japanese name of “Hakko”. As with many of Funakoshi's attempts to rename kata, Hakko (“Eight Storms”) was not adopted by his students, and they kept calling it "Sochin".
How did this kata get into the Shotokan system? Legend says that Funakoshi Yoshitaka was the one who incorporated Sochin in Shotokan. Apparently he set out to train in the Shito-Ryu style and pulled from Mabuni some of his better kata and methods. The result is that Shotokan now contains Nijushiho , Sochin, and Unsu.
In the Shotokan version, the powerful dominant stance in this kata is sōchin-dachi ("rooted stance"). Gichin Funakoshi's son, Yoshitaka was well known to have preferred this stance above all others.
Sōchin is practiced in Shuri Style Karate, not from Naha Style.
Rhythm is important in the execution of this kata. This kata has been said to develop Chi/Ki energy.
Sochin is only known in Shito-ryu and Shotokan
Funakoshi originally tried to rename this kata from its Okinawan name of "Sochin" to a Japanese name of “Hakko”.
Hakko means “Eight Storms”
It was taught in the Naha-te school in Okinawa then learnt by Shito-Ryu masters and then passed to Gichin Funakoshi's son, Yoshitaka who made some changes and became one of Shotokan's kata.
Root: "Shuri-te" school of kata in Okinawa