During the campaign, Koyama council was held as Ieyasu received the news that Mitsunari ISHIDA raised an army in Kamigata (Kansai region), and at that meeting, Masanori, who had been persuaded beforehand by Nakamasa KURODA by Ieyasu's order, readily pledged his allegiance to Ieyasu and preempted the agitation of daimyos caused by Mitsunari's rebellion.
その途中、上方で三成が挙兵した報を受けての小山評定では、家康の意を受けた黒田長政にあらかじめ懐柔されていた正則が三成挙兵に動揺する諸大名の機先を制して、いち早く家康の味方につくことを誓約した。