Seikai is named after his ancestor Miyoshi Seikai, the strongest of the Sanada Ten Braves. He refused to battle at the beginning but when he saw Rokurokubi steal children, he decided to join the fight. He's driven by desire for food, sleep, and women; he also loves video games. He's indecisive, but has unusual strength thanks to his ancestor, being able to get out of virtually any tight spot when he wants to. He corresponds to the "Journey to the West" character Zhu Bajie, the lazy pig. His ninja magic of Ninpo allows him to perform the technique of 'Leaf Hiding Art,' in which he hides in trees and can become temorarily giant to scare enemies. His ninja magic is to enlarge himself temporarily to attack his enemy.