I've Been Killing Slimes for 300 Years but Maxed Out My Level, Vol. 7 (light novel) - Kisetsu Morita - Bog

At level 99, raiding tombs just isn't the same...Ugh, Pecora is exhausting! When she said she wanted a "fluffy elder sister," I didn't think she'd actually turn me into a fox! Sure, I might have caused some trouble at the castle, but it was her fault! And then we went to explore some ancient ruins with Beelzebub and Fighsly, but of course, we can't ever have a normal expedition in this world...Still, it's the little things that make my laid-back life so fun. I even got to meet the goddess who reincarnated me again!(And naturally, Beelzebub herself has more stories to share about her [mis]adventures in the demon lands!)