Board Thread:General Discussion/@comment-24251492-20131204155955/@comment-26420452-20131204175102

Urahara seems to have great potential to be in the Zero Division. The Royal Guard seems to know Urahara very well and based on the way he and Aizen speak on the Soul King, people have said he's met him/it.

However people who are promoted to the Royal Guard need to be Captains (he isn't one anymore, but let's forget this part) who have invented something of great significance that changed forever the history of Shinigami.

Although the Hōgyoku has made a great impact in history for sure, it isn't the breakthrough that can promote you in the Royal Guard because:

1 - it wasn't beneficial to Shinigami

2 - Urahara (and no one else apart from Aizen, even him partially) has control over it.

3 - (I feel that) Urahara is ashamed of the results of its invention.

Urahara has always been modest, he'll carry on living in the Human World while conducting research on God knows what.