Slime Taoshite 300-nen, Shiranai Uchi ni Level Max ni Nattemashita

Synopsis:
After living a painful life as an office worker, Azusa ends up dying from overworking. She finds herself reincarnated as an undying, unaging witch in a new world, and now she vows to spend her days as pleasantly and stress-free as possible. She makes a living by hunting slimes, the easiest targets. But after centuries of doing this simple job, she has become extremely powerful and finds that she can no longer maintain her low-key lifestyle.