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

I`ve Been Killing Slimes for 300 Years and Maxed Out My Level, 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, 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, I've Been Killing Slimes for 300 Years and Maxed Out My Level, Slime 300, 打了300年的史莱姆，不知不觉就练到了满级, La Sorcière invincible tueuse de Slime depuis 300 ans

In this story, a woman named azusa aizawa dies from overwork in her previous life. she is then given the chance to reincarnate into a new world as an immortal witch. however, she soon realizes that even small amounts of experience points can add up after hundreds of years, and she accidentally reaches the maximum level. fearing that her abilities will attract work and force her back to a life of overexertion, azusa decides to hide her strength in order to preserve her peaceful lifestyle. despite her efforts, news of her max level status spreads throughout the land, and a dragon named raika appears seeking to challenge her strength. although azusa defeats raika and befriends her, problems arise as both friends and foes come looking for the secluded witch.