Board Thread:Questions and Answers/@comment-10797017-20130618215950/@comment-11051098-20130627080156

Doesn't the information we have say that the Gotei 13 were created about 1000 years before the story started? Either way, Kyôraku and Ukitake were among the first ones who graduated from the Academy, to become captains. They might not have been a part of the first generation, but they were of the first Academy students to become captains.

Anyway, concerning the original 13 captains, I just got an idea. If you look at the pic of the first generation of captains - [] - the tall individual on the right side of Yamamoto (Yamamoto's left) could be Tenjiro Kirinji. He's tall and slim, and he has IMO the experience and age (having taught Unohana healing spells in the past) that could make him one of the first 13 captains.