Back when the world wasn't in turmoil a released Zanpakuto spirit was next to his wife in a make shift hospital. His name was Seimeiokami he had traveled the world and finally settled down and now was having a kid of his own. On into the night he waited for his kid and as the time stuck midnight he heard the cries of a little cub as he held the baby he saw the characteristics of himself in this babe. He held his son in his hand and named him Chisiokami, but as he saw the light in his son it soon was ebbing away the young cub's spiritual energy was leaving his body.He was dieing. They tried everything that was possible but the doctors that were there were to ill-equipped to save the cub. Knowing the only thing he can do would hurt Seimeiokami heavily but not as much as losing a son, quickly grabbing a empty Zanpakuto and with a heavy sigh sealed his son inside the Zanpakuto.
Amidst all this chaos Seimeiokami didn't realize that his wife had entered into more labored breathing. The shock of him having twins stunned him he couldn't believe it, as the baby was born Seimeiokami saw that he took on the characteristics of his mother. The spirit energy was strong in his newest son. Holding the Zanpakuto that held his first born inside it and with his younger son in his other arm, Seimeiokami noticed that Chisiokami was cracking and breaking he was still losing Reiatsu! Taking Isamu's spirit energy and absorbing some of it into the Zanpakuto knowing that since he was a son of a purely spiritual being he had more than enough to spare, Seimeiokami tied the brothers forever for as long as Isamu had Chisiokami he would keep him alive with the Spiritual energy Isamu possessed, and when he fully unlocked the power of his Zanpakuto, Isamu's Spiritual Power will fully be realized.