Nobunaga the Demon King

Writing a blog about Nobunaga means that, sooner or later, I had to contemplate the issue of Nobunaga as the devilish villain of fiction.
It's one of these "legends" that always manage to piss me off, and I must say that I'm really disappointed when people approach me to tell me that they love Nobunaga too as in Devil Kings he's absolutely badass. ARGH!

*claps hands* May I have your attention please?
The story has its roots in a letter that Luis Frois compiled as one of his annual reports to the Jesuit Company and that mentioned an exchange of letters between Takeda Shingen and Oda Nobunaga.
The report is dated 1573, so the rivalry between the two daimyo was at its apex (Shingen would join the Anti-Nobunaga Alliance on 1572, and he would die a few days after receiving this letter).

The relationship between Nobunaga and Shingen, former allies, turned sour when Nobunaga attacked and burned to the ground the Enryaku-ji, the "mind" of the Ikko Ikki rebellions together with the Hongan-ji, on 1571.
After this fact, Shingen, a fervent Buddhist, gave protection to the survivors of the massacre, among which was Kakujo (覚恕), the head of the Tendai sect (天台座主, Tendai-no-zasu) based in Enryaku-ji.
According to Frois, Shingen made a boast about his role of protector of this fundamental figure for his religion by signing this further declaration of hostility as "Head of Tendai Sramana Shingen" (天台座主沙門信玄, Tendai-no-zasu Shamon Shingen), probably with the implication that he was focused on protecting the head of Tendai, not that he was declaring himself as that.
To "nickname" oneself after the name of a deity was not so absurd, think of Kenshin that considered himself the incarnation of Bishamonten himself-- Anyway, Nobunaga read this and probably thought that Shingen was out of his mind, so he replied ironically, signing his letter with a sarcastic "Demon King of the Sixth Heaven Nobunaga" (第六天魔王信長, Dairokuten Maou Nobunaga), as a way to mock Shingen's pompous nickname, impersonating his exact opposite.
As usual when it comes to the sources coming from Frois' reports, there are no actual sources to compare them with, but they spread and radicate instantly-- And during the centuries, because Nobunaga was making fun of Shingen, he was stuck the role of Satan in every videogame known to history (well, that and the one of the tsundere loli!).

To illustrate this post, I grabbed an image from this blog, that depicts a modern rendition of this legendary signature of Nobunaga.