This is so incredible, what an amazing find.
I don't even know where to start in summarising this, but, a 129 year old magician first became the archmage when she stopped a world threatening demon at the age of 16. She took in 5 disciples as she got older.
At the age of 129, she decided to die by releasing all her mana into the world, but instead she regressed in age because she was never able to experience love (idk). Anyway, she lives in secret with the help of an old friend (love interest). Eventually she tries to find her old disciples because her "death" kinda fucked up their lives.
A lot of cool action scenes happen while she recovers each of her disciples, and their detailed backstories are revealed in the process.
Meanwhile, we wait for a romance to develop between the friend of the FL and the FL.
Charlotte Has Five Disciples