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

Azusa Aizawa, a former salarywoman, is reincarnated into a fantasy world as an immortal witch after suddenly dying from overwork. Her days are spent killing slimes for gold, a life she maintains to avoid the stress of her previous job. However, after accumulating experience points for centuries, Azusa reaches the maximum level, prompting her to hide her abilities to preserve her peaceful lifestyle.