As a descendant of Mitsuhide, Kensaburo believes that he, of all people, should seek to uncover some of the motives behind Mitsuhide`s decision and why he forsake Nobunaga at a time when Nobunaga was in the process of pacifying a nation at war with itself. Using a variety of historical records, both Japanese and Portuguese, Kensaburo looks at the common reasons given for Mitsuhide`s decision and dissects them one by one (warning: major spoiler up ahead).
One of the reasons that I found fascinating was that involving the ties between the Toki (土岐) Akechi family of Mino province and the Toki Ishigai (石谷) family. According to Kensaburo, the Toki, who were originally part of the shugo apparatus in Mino province, sent the Ishigai to Shikoku in service of the Kamakura Bakufu. Following the suppression of the Miyoshi family, the Ishigai came into the service of the Chosokabe (specifically Chosokabe Motochika). As is commonly known, the Chosokabe had played a significant role in Oda Nobunaga`s campaign against the Miyoshi, and had been granted a sizeable amount of Shikoku in return. The Chosokabe also held close relations to the Ashikaga shogunate, particularly Ashikaga Yoshiaki, and Akechi Mitsuhide, as a member of the ashigaru in service of the shogun, had been an intermediary between the Chosokabe and the shogunate.
Kensaburo`s states that one of the prime reasons for Mitsuhide`s act of betrayal had to do with the relationship between the two families of the Toki and Nobunaga`s pending campaign in Shikoku. Given that Chosokabe Motochika had firm ties to the shogunate, a position that put him at odds with Nobunaga, it was only a matter of time before Nobunaga chose to turn his attention towards suppressing the Chosokabe and other families within the Shikoku region. This would, of course, mean that the existence of the Ishigai would be put at risk. At the same time, Mitsuhide was apparently afraid that Nobunaga, once he had completed the conquest of Shikoku and Kyushu, would then launch an attack against the Ming court in China (as Nobunaga himself had expressed a desire to take his campaign to the mainland.)
Kensaburo`s also looks at one of the more famous incidents in the relationship between Mitsuhide and Nobunaga, that in which Nobunaga, in a fit of rage at Mitsuhide`s refusal to acquiesce to his demands, kicked Mitsuhide a number of times and humiliated him. As Kensaburo points out, this apparent incident was not directly witnessed by any of Nobunaga`s retainers, and was based on heresay. As for why Nobunaga would choose to physically attack one of his most senior retainers (as by this stage Mitsuhide had entered into Nobunaga`s service and proven his worth in campaigns against the Ikko sect and Enryakuji), Kensaburo says that it was Nobunaga`s plan to eliminate Matsudaira Ieyasu (later Tokugawa Ieyasu) in the wake of the destruction of the Takeda family of Kai province that pushed Mitsuhide to disagree with Nobunaga and attempt to reason with him.
Kensaburo then goes on to state that Ieyasu`s visit to the Kinki region in 1582, ostensibly to the port city of Sakai and later to Kyoto itself, was part of a plan hatched by Nobunaga to entrap Ieyasu and eliminate him as a potential rival. Only, Mitsuhide, who was privy to this plan, and who knew that if Nobunaga was successful, that he would launch his campaign in Shikoku, a campaign that might ultimately result in the elimination of a close relative to the Akechi and untold horror for many years to come. Hence this also points to the reason why Nobunaga was comparatively unarmed when he entered Kyoto to take up his residency at Honnoji temple. He expected that Mitsuhide would announce that he would travel to the Chugoku region to join Hashiba Hideyoshi (later Toyotomi Hideyoshi), then lead his troops back to Kyoto, surround Ieyasu as he approached the capital, and remove him as a threat to Nobunaga.
However Mitsuhide, driven by his concerns, decided to betray Nobunaga in the hope that this would produce a more favourable outcome for both him and others who had grown alarmed at Nobunaga`s level of ambition and refusal to heed the advice of his senior retainers.
The book itself is clearly written for the novice historian and general reader, and so does not concern itself greatly with masses of contemporary text (in part because evidence of Mitsuhide`s motives is few and far between), and any premodern text that is quoted is given a modern translation with analysis in order to clarify what the original author had intended to say. While Kensaburo does try to reach a justification for each of his conclusions, there is a sense that his study has not yet explored all of the possible sources available in relation to the incident, and so the book cannot be called a `definitive` account of the Honnoji incident.
That being said, it is still a very vivid, simply yet provocatively written work, and one that would serve as a good introduction to any reader interested in exploring the background to the Honnoji incident further. No English translation yet exists for its text, however should I find time I shall endeavour to bring this book to the attention of a wider audience. Two thumbs up.