Katakiuchi nito eiyûki (A tale of revenge and great courage on two islands: 復讐二島英勇記) draws upon the many legends of the historical Miyamoto Musashi (c.1584-1645; 宮本 武蔵), whose name meant "Storehouse of military knowledge."
Born in Mimasaka or Harima, Japan, he was a legendary swordsman and the son of the celebrated fencing master Yoshioka Tarozaemon, a retainer of the Ashikaga shôgun Yoshiteru. Musashi was a bold and reputedly reckless adventurer who nevertheless survived armed combat more than 60 times and died a
natural death on June 13, 1645 in Higo. Katakiuchi nitô no eiyûki was one of the many popular tales of vengeance and retribution, "revenge plays" called katakiuchi mono (敵討物) or adauchi mono (仇打ち物). In
one such incident, Musashi adroitly used a wooden sword — a deadly weapon in the hands of a master — to slay the murderer
of his father. Today, Musashi is widely known as the author of Gorin no sho (The Book of Five Rings: 五輪書), a book on military tactics, strategy, and philosophy. After its first English translation in 1974, the treatise captured the popular imagination and was seriously studied by business executives in the West to understand Japanese management techniques and strategies.
Kasahara Rôô is the theatrical name for the celebrated fencing master Tsukahara Bokuden (塚原卜伝 1489-1571), whom Musashi encountered after
getting lost in the mountains. As Musashi bragged about his exploits, Rôô (literally "old man") laughed,
whereupon Musashi attacked him. Kasawara easily parried the young hot-head's sword thrusts — with a saucepan lid! Musashi
then discovered Kasawara's identity, apologised, and stayed to learn more advanced fighting techniques. Katakiuchi nitô
no eiyûki apparently conflated this legend with another wherein Musashi slayed a tengu ("heavenly dog,"
a goblin of great strength and cunning dwelling in mountain forests). In Hokushû's design we see Kasahara's wings —
often associated with the tengu — as he floats upon a cloud.
References: IKBYS-I, no. 107; IKB-I, 1-417; KNP-6, p. 81; KNZ, no. 127