So much for Sagara being the true final boss. What a tease, damn that Urobuchi and his wicked ways.
To be honest, I never saw Sagara as the final boss. All that got thrown out once he gave Kouta Jimber Lemon (which bumped him to non-jerk Kyubey). And then
Takatora ended up being "Not Ouja," Ryouma threw himself off the building and Micchy had his mental breakdown. But at least Kaito gave Kouta a hell of a fight