I understand the historical naming conventions and the various names Miyamoto Musashi used throughout his life. Miyamoto Musashi is indeed one of the most famous and influential swordsmen in Japanese history. He is a legendary figure whose legacy is defined not just by his martial exploits, but also by his philosophical writings. His most famous work is The Book of Five Rings (Go Rin No Sho), a treatise on strategy, discipline, and philosophy that is still studied widely today in both martial arts and business circles. He founded the Niten Ichi-ryū style of Japanese swordsmanship, known for its distinctive dual-wielding technique, which translates to "two heavens as one" or "two swords as one
The names Niten Dōraku, Bushū, and Bukō all refer to the legendary Japanese swordsman, philosopher, and writer Miyamoto Musashi (c. 1584–1645). Niten Dōraku (二天道楽) Meaning: This was Musashi's Buddhist/dharma name, or spiritual name, given to him in his old age by his monastic friend Akiyama Wanao while in Kumamoto. It can be translated as "Niten dilettante" or "two heavens delight/pleasure". Significance: "Niten" refers to his renowned two-sword style, which he named the Niten Ichi-ryū (二天一流) school of swordsmanship. The "dilettante" aspect is sometimes interpreted as an expression of his humility, considering himself an eternal student of the sword way. Bushū (武州) and Bukō (武公) Meaning: These were sobriquets (honorary titles) used by his followers and in historical records to refer to Musashi with respect. Bushū is an old, respectful way of referring to the province of Musashi (now part of modern-day Tokyo, Saitama, and Kanagawa prefectures), his place of origin. The historical document Bushū denraiki ("An Introduction to Bushū") uses this name. Bukō translates to "military leader" or "martial lord". The chronicle Bukōden uses this title to honor him as a great warrior. Miyamoto Musashi is celebrated for his undefeated record in over 60 duels, authoring the influential strategy text The Book of Five Rings (Go Rin No Sho), and the shorter philosophical work The Path of Aloneness (Dokkōdō), which outlines his life's philosophy in 21 precepts.