Bontenmaru is the second member of the Shiseiten to appear in the narrative. He is arrogant and obsessed with his own legend, frequently reminding everyone that he will become the ruler of the world, and that both Tokugawa Ieyasu and the Mibu Clan will be destroyed so he can become Shogun. This often annoys and bores his traveling companions. Despite this, he is a loyal friend and a formidable enemy.
Bontenmaru harbors a beast within him, which is what makes him truly terrifying. His real name is Date Masamune, known as the "Oda Nobunaga of the north." His weapon of choice is a Bokken, a wooden sword. He is so skilled with it that he can use it against steel swords, instinctively turning it at the last moment to absorb blows without breaking. He can also easily kill enemies with a wooden sword. By using his Satsujintai fighting technique, he can unleash the beast within himself, entering a berserker rage where he tears apart foes with his bare hands. His immense strength serves as his primary weapon in battle.
He can effortlessly defeat small groups of Mibu warriors without sustaining any injuries. His muscles are strong enough to stop blades from piercing his skin. Bontenmaru shares a friendly rivalry with Kyo, and much of their time together involves glaring at each other and trying to establish dominance. His Satsujintai is a hand-to-hand combat technique, and his most powerful move is the Kosoga. In this technique, he swings one fist upward in an uppercut motion and another downward to form a vertical pincer, capable of breaking bones or creating massive craters. (This technique can also be used horizontally.)
