*ahem* My theory is about Kaien Shiba & Ichigo Kurosaki. I believe Ichigo to be Kaien Shiba reincarnated for the following reasons:
1. Kaien was an upbeat and kind, young man who treated all his subordinates equally, though his initial introduction depicted him as rough-mannered. He was shown to be easily annoyed, but usually because he felt others were putting themselves down unnecessarily (e.g. Rukia Kuchiki) or because of Sentaro Kotsubaki and Kiyone Kotetsu's antics. He was a father/older brother figure to Rukia. He was also a prodigy amongst shinigami; graduating from a six year curriculum in just one year and becoming a lieutenant five years after.
^ similar personality to Ichigo + that he was a prodigy could link to Ichigos natural soul reaping talent & ability to see ghost (which may be traits from his past life)
2. In terms of appearance, and in some cases, personality, Kaien had an uncanny resemblance to the series' protagonist, Ichigo Kurosaki. Kaien's hair is spiky, long in the back, and black. (resemblance may have been why Rukia gave him her powers & seems to have affection for him)
Kaien Shiba
Ichigo Kurosaki(predicts that Ukitake may pick Ichigo as his new lieutenant)
information source http://www.answers.com/topic/kaien-shiba
Things to discuss:
My theory: possible holes in my theory, things that support it, ect.
Is there life after death after life after death?: If no why? If yes which one of my theories do you believe? If none of mine make up your own theory and explain it?
Anime/Manga Spoilers: post any spoilers you know that prove or disprove me.
