Maxi is a popular idol and surprisingly, also a best-selling author—something she shares with Kirihime. She's known for constantly throwing around her catchphrase "Shining," which has kind of become her thing at this point.
She's one of three young best-selling authors alongside Kirihime and Momiji, though here's where it gets funny: she doesn't actually know who the third one is. Because of this, she's fixated on Kirihime as her rival and will literally follow her around, using her bodyguards to pull off ridiculous stunts just to get a reaction or mess with her. It's become this whole competitive dynamic where Maxi's always trying to one-up her or get under her skin.
There's also a running joke that Daimon basically has to babysit her because she has this annoying habit of sneaking off in the middle of jobs. Someone's always having to go fetch her when she disappears.
Content compiled by AnimeList.moe from publicly available sources.