Maybe it’s the Kyoto Animation connection that made comparisons with Key stuff inevitable, especially when everyone’s crying. But Shoji Gatoh’s Kanie is the type of character that Maeda and Co. have never convincingly managed to create. Clannad’s Tomoya might be a “delinquent” because they say he is, but what we see is him being selfless and helpful throughout the story. It’d be a pretty short game and a very bad anime (wait…) if he weren’t so helpful.
But Kanie… he’s as stuck up as most people believe his namesake to be, and he’s an abusive jerk to everyone at the park, especially Sento. What we see in the finale is a guy putting that act on again as he comes back to run the park. Everyone has seen the softer side of Kanie, the caring kid desperate to help his friends.
This is character growth 101. Nothing fancy. Kanie is more or less a one-dimensional guy who goes through a very simple arc of change. But changing just that one dimension makes for a lot more impact in the triumphant or teary moments of the climax than letting a one-dimensional guy just kind of stay that way.