Bankai training.
To start training for Bankai you must be at least level 15 you must post one training post consisting of 2.4k words in this area, the total 2.4k words don’t have to be all in one post (this is one of the few places the double posting is tolerated) in your post you must have at least you and your zanpakuto spirit – your spirit will set you a challenge, you must overcome this challenge and get your zanpakuto spirit to submit to you.
When you a done a mod or admin will look over it, you are then free to post up your Bankai.