スライム倒して300年、知らないうちにレベルMAXになってました

Very ordinary company OL (Office Lady), Azusa Aizawa died from overwork. For that reason, I decided to live a slow life at a house in the mountain as a Immortal witch of with a figure of 17 years old. The main source of income is to defeat slime inhabiting nearby to acquire magic stones. I sold this at the Guild at the village. Besides, I made medicinal herbs,Appreciated as The Witch of the Highlands and lived with respect and trust. However, as a result of continuing her life to beat Slime for 300 years, experience values accumulated too much, and unknowingly became level 99 the worlds strongest witch .