Mito: You must already have felt it right? the Kyuubi.
Aizen: Yes indeed I have, a Bijuu chakra is really something incredible.
Mito: The thing is that I want your help when I transfer the Kyuubi to the new Jinchuriki, as I can see *looks at a bunch o wooden clones roaming around the library* you posses the [Mokuton] so want your help in case things go south, having someone with the [Mokuton] can help suppress the tailed beast, and if you agree to help me I can even give you some lessons in Fuinjutsu.
Aizen: I Accept your request Mito, It would be quite good to have someone teaching me Fuinjutsu its one of the things that I struggle to learn.
Mito: no problem just help me that I will help you.
Finishing the talk Mito returned to her house while I returned to doing my things, exercising and doing my training with my clones reading the books of the library, at night I would call back my clone sand sleep while I process the new information that I have acquired.
The days passed like that until the day of my debut on the Anbu, reaching the address the Hokage has given to me a member Inu to be exact greets me, and says that he will give me a tour of the place.
The place is a labyrinth and this is made purposefully as to confuse some spy or invaders, there is a lot of false doors, no purpose corridors even some fake deposits, if you want a picture of it you can compare it to an Orochimaru hideout but more confusing, Inu that has been guiding me through the corridor explaining the place and the sequences I have to follow.
Reaching an opening on the wall there is a counter where I am given my uniform and mask, from now own I am Ocelot.
Now with my new uniform Inu and I went to the rest of the tour, a library where I can read anything B-rank and bellow the A and S rank stuff is from the special reward you gain doing missions top-ranked missions, a place with all kinds of tools from a simple sword to some weapons that I don't even know that can exist, them he stopped on the quarters saying that all Anbu integrants have a simple room here at the base where they can live, they even have a cafeteria, there is also the training equipment room where you can get all kind of things to help you train and last but not least the sparring ring where an Anbu can fight to his hearth content provided he doesn't kill or main his enemy permanently.
Reaching the sparring ring Inu explains to me that is pretty common that I have a spar with the commander for him to gauge my abilities principally with ninja stuff like stealth infiltration and other things related to Anbu the black ops.