Transmigrating Into Miraculous Ladybug, I Transfer to the Protagonists' High School

The protagonist transmigrates into Miraculous: Tales of Ladybug & Cat Noir. They are a candidate Guardian from the Guardian Temple, just like Master Fu, and they belong to the same generation as him. But because the protagonist has the ability to live forever, they never age. The protagonist also has the ability to travel through time, as well as a System. This leads them to acquire other Kwamis and sets off a series of adventures.