Hapi is a character from Fire Emblem: Three Houses.
As a result of magical experimentation done on her, Hapi summons monsters when she sighs. It's a problem. As a result of this, she lives in the church's weird sin basement, separated from the people who actually matter so she can't accidentally hurt them. Because of the potential harm that she could do if she were to accidentally express displeasure at the wrong time, she's more frank than perhaps most people think she ought to be with her negative thoughts to avoid holding them in and causing disaster.
She's either 20 or 25 depending on canonpoint and I'm fairly agnostic with regards to when chronologically I play her from - icons are post-timeskip (25) because I think her hair looks cuter at that point rather than for any deep character reason.