Later in the series, the spirit powers of two other students in Ichigo's school will also awaken as a direct result of personal encounters with the spirit world; while a third is discovered to be a secret warrior in the ongoing battle to protect humanity from the Hollows.
However, the series takes great care to emphasise that the vast majority of people live their lives without ever realising that this other world exists all around them. While the Soul Reapers have tools which assist this continued lack of awareness, they are rarely needed. Until Rukia takes on her human body, no one except Ichigo is able to see her. Even when Hollows are at their most destructive, most human beings can't see, sometimes even refuse to see: and many, including Ichigo himself, try to come up with rational explanations for what they cannot understand until rationalisation is no longer possible.
In the central mythos of Bleach, humans souls come to the Soul Society at death, to be reborn years or centuries later into the world of the living in a vast cosmic balance. Even Hollows are not so much killed as freed from their unhealthy attachment to a world of which they should no longer be a part. The purpose and duty of the Soul Reaper is to protect this cosmic balance at any cost. Emotional and other merely "human" considerations have no place in the Soul Reaper's samurai-like focus on duty, a parallel further emphasised by the outfit of the Soul Reaper and by the symbol and focus of the Soul Reaper's power, the spirit-sword, or zanpakuto.
White, the undyed or bleached lack of all colour, is traditionally a symbol of death and mourning in eastern cultures; but it is also the colour of emptiness and thus of beginnings. In Pure Land Buddhism, white represents the Buddhist interrum paradise where souls are brought to help them achieve enlightenment, and from which a few enlightened souls will return to help other Buddhists arrive at the Pure Land. (Interestingly, later episodes in the series make it clear that Soul Reapers were themselves once human.) In many ways black, its polar opposite, is also its complement: death, yes, but also enlightened awareness sharing its knowledge, wisdom, and power while seeking to learn anew. In English, the words "black" and "bleach" even derive from the same root word. In the black and white world of the Soul Reapers, the orange-haired Ichigo continually inserts a jagged element of awkward humanity into Soul Reaper abstraction.
Like so many other top-quality anime series, Bleach is adapted from a manga, or graphic story (comic book), which has been running in Weekly Shonen Jump magazine since 2001. While many manga-based anime soon run into the problem of getting ahead of the existing manga storyline, Bleach takes its time developing individual character storylines, and thus ends up with some of the best developed personalities in the entire field. Consequently this anime does demand a little more active work than most on the part of the viewer: but it is well worth the effort.
