Our quest against the Templars and Shinbakufu in Japan isn't just driven by a lust for revenge. At the very start of Assassin's Creed Shadows, Naoe is told to protect a mysterious box by her father, and later vows to retrieve it after it's stolen. We don't know what's inside until the very end of the game, but clearly it's important enough that we're willing to skewer every member of the Hundred Demons to get it back.
Spoilers for Assassin's Creed Shadows.
I'm sure we all had our theories about its contents while we were hunting down targets across Kansai, slaughtering Shinbakufu as we demanded answers — maybe it's an Isu artefact, capable of bending minds to the wielder's whims. But the real answer is more rooted in reality.
"It is set up as this important object that can change the world if in the wrong hands. Fast forward to the end, and all that's in the box are the crown jewels of the Japanese emperor, which the Portuguese Templars wanted to steal, for money... MONEY!" u/ZmentAdverti posted. "It's stupid. I don't see the importance of these jewels being so high that it ends up driving Naoe to do all she...