Over the course of the First Warring States Period, opinions on both Demons and Westerners differed greatly between Nihon's clans. The man who would unify the country, Oda Nobunaga, had a favourable outlook on both. In fact, the Oda Clan's fair treatment of Demons and fielding of Demonic troops, even as the rest of humanity suffered under Demonic yoke, earned Nobunaga the epithet of "The Demon King of Sixth Heaven (第六天魔王)."

In late June of 1582, on a warm night, just before the dawn, a traitorous retainer, Akechi Mitsuhide, staged an attack on Honnō-ji Temple in an attempt on Nobunaga's life. This would prove to be a mistake, as Nobunaga had courted a very favourable reputation with the local Oni, who came to the warlord's aid as soon as they saw fire from the temple grounds. The Battle of Honnō-ji would last until sunrise, and an estimated 6,000 deaths would stain the grounds for years to come.

At 8 AM, with the morning sun rising over the hills, Nobunaga forced Mitsuhide to commit ritual suicide, acting as his would-be assassin's kaishakunin. Over the course of one night, Oda Nobunaga had lost his son, Nobutada, his concubine Ranmaru, and many of his generals, but in one swift show of force he had won the country. The Warring States Period ended in 1584, with a formal declaration of unification, but many historians consider the true end date to be June 21st of 1582, the Battle of Honnō-ji.

It is with Nobunaga's conquest of Nihon that the tradition of naming the country after its ruling clan began. Many texts from this period refer to Nihon as the Land of Oda.