Meiboku Sendai hagi (The Disputed Succession)

Nikki Danjo transforms himself into a rat, and by this means he enters Sendai castle in order to find a document that would allow him to get control of the Date family's land. There follows a spectacular series of "quick change" scenes in which the actor transforms into a rat, and then back into a human being.
 

Here a faithful retainer of the Date family defends himself against Nikki Danjo as the rat. How can we tell that the retainer is a powerful good guy?