Ok here is the basic story I came up with, of course, this story is for the game and as such would not contain any of my made up characters.
10 years prier to the Aizen incident, strange things have begun happening. Ichigo has disappeared and so has many of his friends, the former captains of soul society have all either retired of died and as such soul society has started a new. But there is something dark on the horizon, something evil something that would change the world as we know it.
In his absence Ichigo had been training, hard, for many years, he had stumbled upon a power so great, so monstrous that it corrupted even him.
He discovered or better yet created the Arata Hanshoku, the new breed. The Mononoke (quick fact, Mononoke in Japanese means phantom). A breed so powerful, they could bend the barriers of space.
Mononoke are formed when a person does not only defeat their inner hollow, but kill it completely, absorbing it into their soul directly. Ichigo soon discovered that not only shinigami, but all races had a inner hollow, every race capable of controlling reiatsu and he soon played on this. He found and recruited all his former friends and as such made them into Mononoke, for only he could. He would put on his hollow mask and bite them on the neck invading their soul and beating their inner hollow half to death, he would then summon them inside their own soul and make them finish the hollow off themselves in turn making them Mononoke.
Even after all this, Ichigo still was not satisfied, he needed more power and so, he obtained it, by absorbing his swords spirit diretly into his body he made himself and his sword one, and from this discovered the level that no one had ever reached before, Onikai, complete binding with ones sword. (q.f. Oni in Japanese means spirit)
Ok, that is a basic over view of the story it gets alot deeper but that is for later on....oh screw it im going to tell you now
Ichigo then over took Hueco Mundo and Rebuilt Las Noches ruling over all hollows and recreated the arrancar. Also, in the deepest darkest depths of Hueco Mundo he found a mysterious ruins, he searched it, day in and day out and finally found a dungeon deep down within the ruin, in this dungeon he found a man...a man with no name. The man was bound with reiatsu sicking chains around his entire body, the chains were connected to four pilers which had strange marking on them, which turned out to be seals. After what seemed to a years of speaking to and learning from this man, Ichigo discovered that this man had sealed himself here to protect the world from himself, for he was the Omega, the end, the first Shinigami! He had mastered every fighting style and created every kido, he himself wielded four zanpukto, Eternal: Flame, Eternal: Water, Eternal: Wind and finally Eternal: Earth. When these four swords were called forth they combined to make a gigantic zanpukto Known as Hahaoya, the zanpukto from which all others were born (Q.F. Hahaoya means mother). One would push their hand through the sword, their hand would go through like the sword was made of water, and would feel many handles passing their hand, the one they grabbed and drew out would be their destined zanpukto.
Ichigo begged Omega for his help, and as such Omega thought ichigo how to release two of the four seals, just so he could move his upper body and use his Zanpukto. Now Ichigo truly had it all, not only could he make his friends into Mononoke, he could give all of them Zanpukto as well!
Now for the pics
Mononoke Ichigo
Mononoke Ichigo Bankai or Mononoke Release
Mononoke Ichigo Onikai or Mononoke True Form
Ichigo changing Orihime into a Mononoke
Mononoke Rukia
Mononoke Renji
Mononoke Ishida