Tsukikage couldn't understand what is going on. Yuya and Yuzu knew that Sora Shiun'in is working for Academia, yet they still wanted to be friends with him.
It probably must have something to do with how much time he spent with them. They tried to make him show the error of his ways, that he doesn't have to work for Academia to make everyone suffer for the Professor's goals. Sora didn't have any friends when he was in Fusion Dimension, being too focused on being a soldier. That fateful encounter with them really changed that.
At first his relationship with them was for his own benefit but he gradually found real friendship in them, something he doesn't have when he was serving his time as a soldier for Academia. They reached out for him, still believing him despite know his true allegiance. They could wish for him to change his ways.
And they succeeded. Tsukikage couldn't understand how Yuya and Yuzu are able to make friendship with someone who began his path as an enemy.
Perhaps some friendships began this way. You find an enemy, be friends with him, convince him to have real friendships with them, and convince him to turn away from the path of darkness. People can change, and that's what happened to Sora. It's all thanks to being friends with Yuya and Yuzu that he has changed for the better, even finding a smile in him if Yuya had the chance to see him again.
Tsukikage knows that grudges are never ending, but if Yuya and Yuzu can trust Sora, then perhaps he might try trusting him.
Author's Note: Just a short reflection fanfic for Tsukikage.