As Shorin is the Japanese form of "Shaolin", so Shorinji is the Japanese version of "Shaolin-tzu", a tribute to the Shaolin temple in China. Due to the generic nature of the name, five styles with that name exist. Although three of the styles named Shorinji Ryu owe their origins to students of Chotoku Kyan, these five styles are no more closely related to one another than they are to styles with totally different names. Only one of these styles, Japanese Shorinji Ryu, is the closest to what is taught at my club. So, to outline the five styles that all happened to be named Shorinji Ryu:
Okinawan Shorinji Ryu
Founded by Joen Nakazato (1922-present) who based it directly on the teachings of Chotoku Kyan and preserves the original Shuri-te katas.
Shorinji Ryu Renshinkan
Founded by Isamu Tamotsu (1920-present) who places more emphasis on fighting plus more kicking, evasive techniques, and higher stances than other styles.
Shorinji Ryu Kenkokan
Founded by Kori Histaka (1907-1988) in 1945, it combines the teachings of Chotoku Kyan with various Chinese influences (including Chinese Shorinji Kempo). Japanese Shorinji Kempo (also registered as a Japanese religion) was founded by Hisataka's student Doshin So (1911-present) in 1946 and is related only distantly to any form of karate.
Sakugawa Koshiki Shorinji Ryu
This style attempts to preserve the original katas of Sakugawa which he learnt in China, hence "Sakugawa Orthodox (koshiki) Shaolin-tzu (shorinji) Style (ryu)". It was brought over to the United States in 1969.
Japanese Shorinji Ryu Richard Kim (1917-present) brought this style to North America and began teaching in San Francisco, California in 1959, but its origin is rather cloudy. Some sources state that he teaches the same Shorinji Ryu as Kori Hisataka, but that is not true at all. He has been taught by Kentsu Yabu, Gogen Yamaguchi, and others. He has taught Goju Ryu, Shotokan, but most importantly Shorinji Ryu (modified with elements of aikijutsu and Shotokan karate). It is not clear in existing written literature who taught him Shorinji Ryu. So, I e-mailed the Butokukai, the Japanese martial arts organization of which Richard Kim is the U.S. head, and asked. Through an intermediary, Richard Kim informed me that "My Shorinju sic] Ryu is from Yabu Kentsu".
Zen Nippon Shorinji ryu Karatedo is a relatively small style compared to the "big ones" such as Shotokan or Wado-ryu. The style is also known as Zen Nippon Shorin-ji ryu Renshin-kan Karate-do in Japan. There are some 400 000 people practising the style in Japan and some more outside of Japan. In the USA there are active shorinji ryu karatekas. In Finland, it is (at least from the statistical point of view) the most popular style. Shorinji ryu is known and famous for its spinning and jumping techniques. Kicks are favoured in ratio 70%-30% to punches. The use of footwork and evasions is similar to old schools of ju-jutsu (ko-ryu ju-jutsu) and aikido; the main purpose is not to meet force with force but to use body-evasions and footwork combined with kicks and punches used both in blocking and counter-attacking. This approach (to fighting) is very different compared to many modern styles of karatedo, yet truly effective. The stances are relatively high and narrow compared to e.g. Shotokan.
History
Zen Nippon Shorinji ryu Karatedo renmei was founded by renmei soke Tamotsu Isamu (b. 1920), 10. dan in 1955. Tamotsu practised several different martial arts in China, Taiwan and Japan. He studied the techniques especially for their usefulness in actual combat. He also emphasized combining the nature and contents of budo to karate and making the difference between katsujinken ("life bringing") and satsujinken ("life destroying") techniques. He also participated in developing a safe way to spar by using protective body armour and helmet. He felt this to be a good way to study the true power and effectiveness of kicking and punching techniques, simultaneously allowing for a safe way for competition matches. Tamotsu's greatest influence was an established martial arts teacher Kyan Chotoku. Kyan was known for his ability to integrate jumping in his techniques and this shows even today in the styles developed by him and his students. In literature it is mentioned that Tamotsu studied under Nakazato Joen, the founder of Okinawan Shorinji ryu Karatedo renmei [Patrick McCarthy: Classical Kata of Okinawan Karate, Ohara Publications]. Sensei Matsuoi has mentioned that Tamotsu's teacher was Nakamura Shigeru, 10. dan. Also the name of Shimabukuro Zenryo, 10. dan has come up in the discussions concerning Tamotsu's numerous teachers.