Why all speculation only involves Ichigo and not either Orihime or Sado? Both of them possess powers that exceed normal humans and Orihime also has special type of abilities that are sought after by both Aizen and Soul Society. I will be damn pissed if by the end of Bleach manga, there will be no back story on how come Orihime has hidden latent super abilities as a "mere" human.

Mind you that this explanation was told quite early in the manga. At that time even Ichigo was supposed to be a normal human that's "somehow" blessed with Shinigami power (this was before Shinigami Isshin got revealed way later in the manga). So this Ichigo reatsu leaking thing only serve for a temporary convenience explanation for both Orihime & Sado.

Come to think of it, even Ichigo childhood friend also affected by this reatsu leaking thingy but all she can do is only barely detecting & visualizing the physical form of hollow. That's all. Meanwhile both Orihime & Sado already miraculously achieved OVER NINE THOUSAND!!!!! of powers. There must be more than that to explain the origin of Orihime & Sado powers now.