Iga Ninjutsu is Good (Hattori: Legendary, Domination, V5445)

[Maltz]

Chisato: "The Ashikaga samurais are shattered! They run for their lives!"
Goemon: "These samurai never had any battle experience... like they were fresh made from factory. They can't bear the cruelty of darkness, the descent of the angel of the night!"

Note: If war is declared upon the Ashikaga Shogunate, a full stack will be created by the game's script just outside Kyoto. This army is featured in the battle.

However, in my personal experience the second full stack does not always spawn. I am not certain why I could avoid it sometimes. Maybe I declared war upon the Shogunnate via an ally, who was at war with the Ashikaga. Or maybe there were other factors.