It is hard to precisely translate the word Nin, the closest sense being that of “perseverance”, “patience”, “hidden” or “to endure”.
The Nin kanji is composed of two parts, the upper one, yaiba, means the sharp edge of a blade and the lower part is read as kokoro or shin and it means the heart.
This means that a person gifted with these virtues, patience,

perseverance, will prevail in anything he has to do, even with a sword or a dagger clenched in his heart. Many people instantly think about the famous Ninja warriors when they hear this word and, of course, about their art – Ninjutsu.

We wish to underline the fact that the term Nin does not necessarily refer to the Ninja, tough it represents a significant part of this word it can also be used to write another very important word found in the teachings of all martial arts, the word Nintai or “the spirit of perseverance”.
This word is often used for the oral transmission of martial arts schools, without necessarily linking it to the Ninja. Bu refers to “martial”, “warrior”, “knight”, and, in general to all pertaining to the practice of martial, warrior arts. Furthermore, the Bu kanji, if separated in two parts it also signifies stopping the fight or the correct practice of martial arts. Kan means “building” but in our case it can also be translated as “place of training - dojo”.

The significant idea is that Ninbukan represents “the place where warrior who train in martial arts learn the correct practice of these arts, and also they attain the spirit of perseverance in any domain”,

according to the Ryogen Ryu motto “Issho kenmei monogoto o suru koto” which is translated by “always making desperate efforts to follow thru in ones actions” (always doing everything in your power as you would protecting something or someone, even with the price of you life!).

We need to concentrate our efforts as if our life would be at risk or as if we would find ourselves in a life and death situation, because this is the only those who practice martial arts can be successful!