History does not remember Oda Nobunaga kindly. Every video game, movie, and anime adaptation I’ve seen has portrayed him as nefarious and unhinged. And believe me, you don’t really have to look that far to discover why.
Nobunaga was a fearsome general. His main goal was to unite all of Japan, but peace talks were not his style. Nobunaga started civil wars with damn near every territory he encountered. And to his credit, he didn’t lose a single one. As a general, Nobunaga was a genius akin to George Washington. But as a person, he was closer to William Sherman.
As I mentioned above, there are clear-cut reasons why Nobunaga is not remembered as a “unifier,” notably because of massacres that Nobunaga enacted. In 1574, Nobunaga succeeded on his third attempt to capture Nagashima—defeating a clan of warrior monks, the Ikkō-ikki. After being victorious, Nobunaga’s men forced the 20,000+ Ikkō back into their strongholds, completely cutting the Ikko off from all supplies. After forcing all the Ikkō inside, Nobunaga burned everything down. Not a single Ikkō of the 20,000+ survived.1
But for his largest atrocity, you have to go back to 1571 at the Siege of Mt. Hiei. The Tendai monks were long time enemies of Nobunaga, as they sided with two clans that opposed him—the Asakura and Azai. These Tendai monks also took up residence on Mt. Hiei, which was directly between two valuable territories—Kyoto and Lake Biya. And well, when one of Nobunaga’s largest enemies is in possession of a very valuable and strategic piece of land, he lacked restraint. Nobunaga’s army started at the base of the mountain, slaughtering and decapitating everyone they encountered. EVERYONE. Women, children, holy men, and prominent figures alike. Then to really slam the door closed on the Tendai monks, Nobunaga had the mountain set on fire. No one survived.2
It is absolutely for these reasons why Nobunaga is not seen favorably (he also may have called himself a Living God; clearly the words of a sane person). But it is no joke as to how much Nobunaga accomplished. He conquered half of Japan in just 22 years. It is highly likely he would have accomplished much more if a general of his, Akechi Mitsuhide, had not betrayed him in 1582. It is highly contended whether Nobunaga burned to death in Mitsuhide’s fire or committed suicide before the fire consumed him.