Our Ningen Zen is an authentic Rinzai Zen School to attain "Kensho"(seeing into one's own real nature) through the introspection of "Koans" to attain enlightenment.
The way of Zen practice carried out at present in Japan has two descents, the Soto School and the Rinzai School.
Dogen zenji (the founder of the Japanese Soto School) pointed out 18 necessary prerequisites as questions in "Shobogenzo Bendowa," of how the real Zen practice should be and indicated the answers to these by himself.
The core of them exists in the 7th question which makes clear that the real Zazen should be the Dharma-Seal of Buddha, stating as follows, "the view that Zazen and enlightenment are quite different is the outsider's mistake. As far as the Dharma transmitted from Buddha is concerned, the practice of Zazen and the Dharma Seal of Buddha are identical. Therefore when the Patriarch confers the precaution about Zen practice, he instructs that there should be no Dharma-Seal separate from Zazen, because it is the evidence directly handed down from Shakyamuni Buddha. Accordingly even now Zen Masters indicate that the practice of Zazen by the beginner should be the whole of Dharma-Seal as it is."
This view indicates that the real Zazen itself is involuntarily the incomparable marvelous Dharma and therefore Zen students should not deal with Zazen as a mere means to attain enlightenment.
Still more Dogen Zenji stated in his "Shobogenzo Genjo Koan," proceeding with this problem as follows, "The view that students devote themselves to Zen practice for the sake of proving the Dharma of every existence is delusive. On the other hand the state that the Dharma itself advances to verify the real selves of students in Zen practice is truthful."
"To learn Tao of Buddha is to learn the self and to learn the self is to forget the self. To forget the self is to verified by the Dharma of every existence."
The characteristic of Dogen Zenji's Zen Buddhism is ultimately the view that Zazen practice by beginners should be the whole of the Dharma-Seal and therefore the learning of the Buddha-Dharma is an action of no utility, like adding frost on snow.
To tell the truth, there is really concealed the jeweled-mirror samadhi of the Buddha in the bases of this view. But this truth is the most difficult secret to understand, needless to say, for a beginner, still even for an old practitioner of Zen Buddhism of over 10 or 20 years.
We should say that it is generally impossible to really attain to this exquisite state of Dharma of the Patriarchs and to perform Tao truly.
C ompared with the Soto School, the pivot of Zen practice of the Rinzai School is to attain "Kensyo." Therefore Zazen itself is not the ultimate object, but the mean to attain enlightenment. Still more, Kensho itself has several grades and ranks in respects of depth, power, broad-mind, or strength of activity, from beginner to Patriarch.
Hence students must go up the steps higher, complying with the request of the systematic order of Koans, after they become enlightened first, until they finally prove the Dharma-Seal of the Patriarchs.
Torei Enji Zenji has described in full details all the aspects of practice of the Rinzai School in his "Shumon Mujin Toron." In old times, the stages of Kensyo were classified into three as follows,
1. Richi (attain Sunya)
2. Kikan (gate of complex interlocking)
3. Kojo (the ultimate elevation).
Hakuin Zenji had classified them into seven as follows,
1. Hosshin (Dharmakaya)
2. Kikan (the complex interlocking)
3. Gonsen (investigation of words)
4. Nanto Nange (difficult to pass through and solve
5. Goi (Five ranks by Tozan Ryokai Zenji)
6. Jujukinkai (Ten Commandments)
7. Matsugo Kojo (the ultimate elevation).
Nowadays, Japanese priests of Zen halls adopt this classification into seven by Hakuin Zenji.
Koun-An Roshi had selected 200 Koans and arranged them in a new order systematically, publishing them as "Gasensyu" openly. This had an epoch-significance on the history of Zen Buddhism.