I've Been Killing Slimes for 300 Years and Maxed Out My Level, Vol. 1

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 Of Doing This Simple Job, She's Ended Up With Insane Powers...how Will She Maintain Her Low Key Life Now?!