If Senju Tobirama chooses as the first successor, Uchiha Kagami. The reason why Senju Tobirama died together for the sake of Konoha was the joint effort of Uchiha and Senju. Uchiha Mirror, who knew the truth, supported Sarutobi Hiruzen's succession. The kaleidoscope of the Uchiha mirror can obtain the memories of others by touching the dying corpse.
Except for Susan, each Mangekyo has two unique skills. So what is the remaining kaleidoscope skill of Uchiha Mirror?
Choice 1: The soul body looks on indifferently. "I will see your destruction with my own eyes."
Choice 2: Reunion of the Warring States Period across time and space. "I wanted to meet you earlier."
Concept: Another development direction of the Naruto world.