“Shin Jin Ichinyo” is an idea found in Togakure-ryu ninjutsu. In the simplest sense, it can mean to be one with “God”, which of course brings up several problems in interpretation. Instead of leaping on to the Judaistic interpretation of what “Heaven”, “Divine”, “God” and so on means. Let’s look at the placement of it’s usage in Japanese Shinto culture – the native spiritual and metaphysical system (I mean this loosely) of Japan.
In shinto (Way of the Divine; 神道), the followers essentially celebrate and worship the various manifestations of the elements of nature, and identify these elements, as well as the manifestations themselves, as entities called kami (spirits, gods, etc; 神). Thus in this understanding, we can see Shinto (神道) to be the way of respecting the manifestations of nature, the tradition of Shinden Fudo-ryu (神傳不動流) to be the “Unchanging transmission of the manifestations of nature”, and we can see Shin Jin Ichinyo to encourage the idea of “harmony between mankind and the natural manifestations of nature, or the “ever-changing nature (Shizen Banka; 自然変化).
I like to talk about this as the expectation of the universe (宇宙) on mankind to be respectful and responsible to our nature, the natural world, and all the myriad manifestations of the elements and their variations. For if we’re selfish, and care only for laziness, ourselves, and the short-term, we only undermine our every gesture and intention. We are not doing things for what is just, virtuous, and right for everyone, not just yourself (after all you are a part of everyone).
According to the Bansenshukai, one must have Benevolence, Righteousness, Loyalty and Fidelity in order to follow the path of the shinobi…