Disclaimer: I am now going to hold forth on a bunch of religious things I don't well understand. I welcome input. Much of this discussion is informed by the text, Kukai: Major Works translated and contextualized by Yoshito S. Hakeda, Columbia UP, 1972.

Mirage Spoilers through volume 40.

Mirage ultimately makes Kagetora a messiah. In the final volumes, he becomes a saintly figure, in the broad sense of a person whose life is defined by compassion and service to others. But more than that, he becomes a savior. Across the text, he is symbolically identified with Jesus: sacrificed by his father, sacrificing his life/soul to bring others peace, symbolically the son of Mary (Minako).

Kagetora also becomes the originator of a new religion, a new mode of existence. He is like Jesus in this as well but more pointedly like Kuukai, the founder of the Shingon Buddhism the Yashashuu practice, with whom he is explicitly identified as "Present Kuukai." His new way is defined by the Shadow Shikoku, a space he helped create at the cost of his own soul's death, where onryou are welcomed and allowed to persist in their present existence as they find their own path forward. Kagetora's new path, I'd argue, fits into the evolution of Buddhism. It is the next step on a trajectory that increasingly values individual life and individual agency.

Some Extremely Reductive Religious History:

Pre-Buddisht Hinduism (I'm thinking of the Bhagavad Gita) has a powerful teaching about reaching enlightenment, but it closely ties this journey to caste and to duty in the world. The idea is that (at least usually) people need to be reborn through different caste roles in order to work through their karma and reach enlightenment. "Dharma," here, refers to proper individual action/duty but also to a larger sense of balance in the world, to everyone and everything functioning in its place together.

Gautama diverged strongly from Hinduism in positing that enlightenment wasn't inextricably connected to caste but rather to any individual's spiritual practice. In Buddhism, Wikipedia clarifies for me, "dharma" still suggests the order of the universe but also generally includes the core teachings of Buddhism, which is to say, a system more focused on the individual's spiritual journey and less focused on the individual's social duties. Thus, Buddhism can be said to be significantly more oriented around the individual and less around the community as a whole. [1] However, within this system, it is still generally assumed—as in Hinduism—that any given person will require many lifetimes to work through their karma to enlightenment.

In Kukai: Major Works, Hakeda notes that a key characteristic of Shingon, which sets it apart from other Buddhist schools, is Kuukai's emphasis on the ability to "attain enlightenment in this very existence" (6). Kuukai outlines ten stages on the journey to enlightenment of which the tenth is the ultimate "Esoteric" teaching. Above about stages 4 to 6, they are extremely hard for me to differentiate and certainly do not sound readily attainable in any life—but he was confident that people could do it. Hakeda describes Kuukai as "extremely affirmative and optimistic" (93). And his emphasis on the individual's agency, I would argue, is greater than most Buddhist schools' in that he firmly held that an individual could break free of his karmic burdens within a single lifetime. 

In establishing the Shadow Shikoku, Kagetora builds on the idea of attaining enlightenment "in this very existence." In this concept, individual souls should be able to choose when/whether they wish to be reincarnated. After the body's death, a soul could pass on as usual, be cleansed, and come back in its next life to continue the karmic journey. Or a soul can stay in the Shadow Shikoku with something like a living person's presence and continue the trajectory of that one life, working on one's psyche just as any of us does going through life but with a fairly unlimited span of time. A person could theoretically stay in one life for hundreds of years until reaching enlightenment, or stay in one life until reaching some other benchmark of completion of fatigue and then be reincarnated, or just pass on directly after death in the traditional way.

Kagetora, thus, posits not only that individuals can attain enlightenment within one existence but that there is inherent value in allowing them to choose a particular existence for this work. As a sidebar, I am not sure Kuukai would agree: the idea of attachment to a particular existence runs counter to the idea of impermanence, the realization of which is crucial to all the higher stages moving toward enlightenment. But Kagetora, I think, is more concerned with individuals at the lower stages, those still working through their core problems of attachment. He would like for these people to have the latitude to work through these issues at their own pace in their own way. And this is another quantum leap in the direction of individual choice and individual focus. It shows profound care for the right of the individual to his or her own spiritual journey.

For Kagetora, the desirability of this option is informed by his own life. As a kanshousha, he spent four hundred years working out his issues in one continuous lifetime, and while it was an agonizing journey, ultimately, there is no question he finds it worth every minute. Though I do not think Kagetora himself arrives anywhere near ultimate enlightenment, he does accelerate down that path remarkably fast "in this very existence!" in this last couple of years of life. The sense of inner peace he finally arrives at, his peace with himself, his peace with Naoe, his peace with all the world really (even emotionally with Nobunaga and Miroku) is a revelation he could not have found in that way without being Kagetora all those years. Being a compassionate person, he wants to give everyone else the same chance to find themselves.

So Is It a Good Idea?

However, it's far from clear that this is the most desirable model for human development. For one thing, it throws out of balance the world as it has been. At least one region in Japan is now crowded with spirits, which minimally has to be intrusive for the living people. It also raises questions about the reproductive cycle of souls. If enough people choose not to reincarnate right away, what will happen to the babies whose bodies they would have entered? Will new souls be created? Will this create an unbalance, a soul overpopulation (or literal overcrowding of at least the appearance of people)? Will a lot of families become sterile? Will a lot of children be stillborn? Is this too much of a loss of participation within the larger community? Does it stray too far from the Hindu sense of dharma as the balance of the world?

A different kind of problem is the basic philosophical concept. For centuries, the Yashashuu operate under the assumption that it's fundamentally good to exorcise onryou because it helps them move on in their karmic journey. The Yashashuu feel tremendous pain and suffering in their own lives, largely attributable to living so long uncleansed. So, yes, Kagetora eventually arrives a good place, but there's every reason to think that if he had been reincarnated in the normal way shortly after his original life, he might have arrived at a similar type of peace perhaps faster and with less pain. Is the Shadow Shikoku simply an example of clinging to a stage in existence that is more naturally let go? Is the earlier model (exorcise those spirits) in fact right?

On the other hand, there's no ironclad reason this new system couldn't work. Consider, by analogy, a technology that extends human lives—including bolstering memory as needed—for four hundred years, allowing people to undergo profound experiences in personal development that they would otherwise often die before achieving. That's not necessarily bad. It might produce a world in which the average person is, by our standards, quite wise and balanced. It might bring world peace. (It might be a step in preparing the world for the ultimate enlightenment of the Maitreya Buddha.) But minimally, the world would have to undergo a lot of adjustments to make it work. Most notably, while this life extension is still happening (before it reaches a steady state), people would almost have to stop having children in order to prevent ecologically catastrophic overpopulation.

The preservation of the old comes at the expense of the young, at least in some ways. And this is a central theme of Mirage, a story in which the lives of souls are atypically extended while the lives of a new generation are perpetually preempted. Among the main characters of Mirage, having children virtually never (if ever?) works. This theme extends from childlessness by choice (all the Yashashuu in any post-first life storyline I can recall) all the way to the kind of grotesque child eating of Nobunaga's plans to use his offspring to generate energy for his world domination. In the middle lies a lot of reproductive tragedy. The murder of Kagetora's son is a historical event but fits well thematically. Minako's child, too, is never born, and even if it had been, she would have chosen to exorcise it in order to provide a vessel for Kagetora.

Naoe and Kagetora's sexual connection is often described in reproductive terms (spiritual sperm and pregnancy and so on), but it is not designed to create new life. It is ultimately designed to preserve old life: to merge Naoe's and Kagetora's souls to the point that what is left of Kagetora can be incorporated into Naoe. In a sense, this makes Naoe pregnant with Kagetora, but it is a pregnancy that can never lead to a birth. It is not a genesis but a retention of what is left after death, not a new life but an echo of an old one.

So there's the tradeoff. And it might be worthwhile. It might result in a world in which old souls with great knowledge and life experience are the norm and new births are fairly rare. That might be a good world. (It sounds a little reminiscent of Elvish society in Middle-earth.) But it might also be an abnegation of participation in the cycles of life. It might disrupt the rhythms of life and death.

But however it ends up—it probably won't be either Edenic or hellish—the story does successfully render Kagetora as a messiah, the person who changed the world, as Naoe's future vision has him. He truly does become the next Kuukai. This isn't easy to pull off in literature. And that Mirage is able to sell it is a testament to the care and intricacy it shows in walking through four hundred years of Kagetora's journey from damaged young man to badly broken hero to healed human being to martyred spiritual teacher.

[1] Buddhism's tendency to focus on the individual rather than the community is alluded to in Kuukai's "The Precious Key to the Secret Treasury" in which he mounts a defense of state funding of Buddhist temples against a Confucian argument that they are not useful to the state. The gist of his reply is that Buddhist monks and nuns are useful because they spread the teachings of Buddhism, which help release people from suffering (Kukai 190-91). However, the very need for a defense suggests an awareness that it was not characteristic of Buddhist temples to contribute to the state in obvious, material ways.