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

An at-home comedy about a powerful girl who doesn't work too hard. After dying of overwork in the real world, I'm reincarnated as an immortal witch, and I spend 300 years enjoying a relaxing life. At some point, though, I end up at level 99. All those years spent killing slimes to make the money to pay the bills gave me a ton of experience points - Rumors of the level 99 witch spread, and soon I'm up to my ears in curious adventurers, duelist dragons, and even a monster girl calling me her mom. "This isn't a dojo, so don't come here to fight me...!" I've never been on an adventure, but I'm the strongest in the world - What's going to happen to my relaxing life?.