It's a reboot of a 90s action series, which seems to be pretty well regarded as a bit of a throwback to older anime.
Basically a high school kid gets accidentally walks into a den of intergalactic criminals and blasted by space police officer Birdy. To save his life she transferred his memories into her body and uses her transformation powers to imitate his appearance so he can live some semblance of a normal life while they share the same body.
It sounds cliche, but it actually pulls it off pretty well (better than either of the manga it's based on) and I was pleasantly surprised that it avoided certain tropes. Season 1 is a pretty typical action anime plot, while season 2 is more ploty and personal, examining the aftermath of the first season, Birdy's past, and is a bit more morally ambiguous as it's about Birdy tracking down a vigilante brutally murdering criminals in hiding on earth before they can stand trial.
At any rate you can legally watch it in its entirety for free on Hulu IIRC.
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The only certain death in the universe is Mother Hitton's Littul Kittons.
Not changing this line until I beat Seven Heroes (2/24/07)