Shuiren
A policeman in the December world. Always having a pleasant attitude and often seen with a friendly smile on his face, Shuiren is well-liked by most people. However, his smiles are almost always insincere, and the only person he really cares about is his childhood friend, Aster. She saved his life when he was younger, and so swore to stay loyal to her forever.
When Aster was worried about supporting herself in the future because of her disability, Shuiren promised to take care of her and marry her so she wouldn't have to worry about anything. When Shuiren grew up, he secretly did assassination jobs in order to pay for Aster's medical bills. He doesn't feel any guilt about killing others, but doesn't want Aster to find out, since he knows she'd never approve.
Shuiren is trying to find a way to permanently cure Aster of her disability, and doesn't trust that the Amelis magic that's letting her walk right now will last her forever.
[From offiical bio]
When Aster was worried about supporting herself in the future because of her disability, Shuiren promised to take care of her and marry her so she wouldn't have to worry about anything. When Shuiren grew up, he secretly did assassination jobs in order to pay for Aster's medical bills. He doesn't feel any guilt about killing others, but doesn't want Aster to find out, since he knows she'd never approve.
Shuiren is trying to find a way to permanently cure Aster of her disability, and doesn't trust that the Amelis magic that's letting her walk right now will last her forever.
[From offiical bio]