I've Been Killing Slimes for 300 Years and Maxed Out My Level, Vol. 4

Why do strange things always seem to happen to me?I've lived in this world killing slimes for three hundred years...so how did I turn into a little kid?! I bet it was those mushrooms Halkara cooked...And now everyone in my family is trying to coddle me! Please cut it out! Not only that, but I have traveling minstrels, a World Spirit Summit, and even a demon music festival to worry about...Still, I'm not giving up on my laid-back life!