Guard yourself. Let no one in. Distrust everything and everyone. Only then will you become a true warrior Shihan Matsuda.
Shihan Matsuda was, according to Bruce Wayne, a Zen-Buddhist monk warrior, master of mind control, trained at the hand of Tibetan magicians and martial arts senseis. He lived with his wife in the mountains of the Himalayas and rarely ventured to the small village situated below. Having amassed a small fortune in his native Japan, Matsuda had become heavily paranoid of everything and everyone. His lessons to Bruce Wayne mostly extolled the virtues of distrusting others and suspecting everyone of everything (something Batman obviously took to heart). He also taught Bruce to melt ice simply by sitting in it and thinking warm thoughts, as well as how to cut a flying coconut in half with a katana, but have it land in one piece (which would be, as a certain Monty Python sketch would have it, guaranteed to break the ice at parties). Ultimately, Matsuda died after failing to follow his own advice. His wife (who had been like a mother to Bruce) attempted to murder her husband for his money and, in the resultant fracas, she, Matsuda and the pretty girl from the village (whom Bruce had, of course, become infatuated with) all ended up dead. This is what closeness will bring you, squeaked out a dying Matsuda, as his last breath ebbed away. Matsuda first appeared in the Zero Issue of Detective Comics (September 2012) in a story called The Final Lesson, by Gregg Hurwitz and Tony Daniel.