Story is in a scifi world which looks like an island of multible connected circle islands. The anime wa about a boy who somehow lost his sister and he got into a school. There he met a girl who was a princess of a nearby kindom and who had fire powers in form of flowers. The guy then got a sword which had a retractable purple energy blade and he could yous some kind of overpowered ability to smash everytuing, but then he had to take a break. The school had arranged a tournier where every student could build teams and try to win a prize. I know this is preatty much information, but i watched it like two years ago for free on amazon prime
Pls help because i dont remember the name and i couldnt find it using a similar describtion. Maybe someone who watched it recently knows the name.