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

A centuries-old immortal witch, exhausted from overwork, spends 300 years in relaxation before discovering a new passion: hunting slimes for profit. Reaching level 99, she becomes the world's strongest, attracting a variety of attention from curious adventurers, dueling dragons, and even monster girls who regard her as their mother. However, despite her incredible prowess, she has no interest in combat, and her greatest adventure is only just beginning.