Ona is an extremely strong demon who just happened to bond megan as her familiar during a fight. in the world they live in, everyone has a familiar who is chosen completely randomly and usually has no connection to them. so, ona and Megan are extremely lucky that they are a similar age and get along well. but they're also very unlucky in that, since Megan is of monster hunter descent, they are now forced into becoming government paid "hunters", basically bounty hunters whose job is to take care of dangerous disturbances caused by monsters.

as ona herself is a monster and Megan hates her family, this is a terrible situation, but they try to make the best of it.

ona is really into fighting and is an extremely bad cook. she has a very act now think later type personality, and makes up for being very emotionally unstable and having feelings of inadequacy by acting overly confident and sometimes aggressive. she's pansexual and will flirt with anything that moves, but during fights it's all business (none of that seducing ur enemies bullshit, ona will only participate in a good clean fight)

the only accurate drawing I have of her lol

at the beginning of the story, ona is a very highly regarded demon in her community, marked by her undamaged horns, dozens of scars, and extremely long hair. these are all seen as markers of a good fighter, as they show that the demon is willing to get roughed up but can still protect very vulnerable parts of themselves, like their horns and hair. but of course, becoming a hunter affects this social standing which she also has to deal with.

in the monster hunting duo, ona generally serves as muscle, as demons can only be badly hurt with special weapons or by another demon. she doesn't use weapons, and instead uses her long talon-like fingernails (the only real thing demons have as a special ability) which she is able to grow longer or shorter on command.