User blog comment:Xilinoc/Ch. 599 - Too Early To Win, Too Late To Know/@comment-4822693-20141004225027/@comment-5398287-20141005010710

Hm. That's certainly an interesting theory. I myself (as well as another user in this comment section) was thinking that there are actually unlettered Sternritter, based on how Shaz introduced himself as a Sternritter but without a letter to go along with it - in stark contrast to basically every other Sternritter (e.g. "Sternritter H 'The Heat', Bazz-B!") - and that said Sternritter are still captain-level, but have weaker powers because Yhwach didn't inscribe a letter onto their soul. However, now that I think about it, Haschwalth never stated that there could only be one Sternritter per letter at a given time while he was describing Yhwach's power to share his soul - I had assumed that Royd and Loyd shared the letter because they were twins who were basically born with the same power already present in them and Yhwach just enhanced it in some way, and that Uryu and Yhwach himself shared the same letter because the former was in line to succeed the latter as Emperor of the Wandenreich and that "A" was automatically granted to such individuals.

I agree that Kubo should do something akin to this so that we can see the as-of-yet unknown Shikai, Bankai, and so on of the characters still in Soul Society. I wouldn't mind it as long as he kept the abilities interesting.