Maki appears to have a very serious personality, as she doesn't really seem to smile much if at all. The only notable exception is the poster which shows her with a mysterious smile, having a finger over her lips, which is a sign of secrecy.

Despite her cute appearance, Maki is described as a hostile misanthrope of few words. She is very aware that she comes across as unfriendly and prefers to be alone. In general, she dislikes people and thus she is not very cooperative, and can be stubborn. 

Japanese Voice Reference: https://www.youtube.com/watch?v=NAm9GYZuJOg