I've Been Killing Slimes for 300 Years and Maxed Out My Level

After living a painful life as an office worker, Azusa ended her short life by dying from overworking. So when she found herself reincarnated as an undying, unaging witch in a new world, she vows to spend her days stress free and as pleasantly as possible. She ekes out a living by hunting down the easiest targets - the slimes! But after centuries...