Bontenmaru is the second member of the Shiseiten to appear in the story. Arrogant and in love with his own legend, he constantly reminds everyone that he will become the ruler of the world and that both Tokugawa Ieyasu and the Mibu Clan are going to be destroyed so that he can become Shogun, much to the ire and boredom of his traveling comrades. Nonetheless, he is a great friend as well as a fearsome foe.
Bontenmaru suppresses a beast inside of him, and that's what most terrifying about him. His real name is Date Masamune, the "Oda Nobunaga of the north." His weapon of choice is a Bokken. He is so skilled with it that he is able to use it against a real sword, instinctively turning it at the last second so that it absorbs the blow of a sword but doesn't break. He is also capable of killing an enemy rather easily with a wooden sword. He can unleash the beast within himself using his Satsujintai fighting technique, in which he can enter a berserker rage and tear foes apart with his bare hands. He uses his great strength as a weapon in battle. He can effortlessly defeat small groups of Mibu warriors without getting hurt. His muscles are strong enough to stop blades from piercing his skin.
He has a friendly rivalry with Kyo, and much of their time is spent glaring at each other and trying to establish dominance. His Satsujintai is a hand to hand fighting technique, and his most powerful technique is the Kosoga. He swings one fist upwards in an uppercut motion and another downwards to form a vertical pincer, which can be used to break bones or, at a later stage, create a massive crater. (This technique can also be used horizontally.)