I've Been Killing Slimes for 300 Years and Maxed Out My Level Novel Volume 11 is written by Kisetsu Morita with illustrations by Benio.

I’ve been killing slimes for 300 years and now I’m participating in a relay race?! What kinda alternate world is this? Still, I gave it my all since my family was so into it. After that, I threw a music festival with the moon spirit (Luna Luna!), visited the leviathan sisters on their day off, and then my daughters ran away from home… Wait, what?! Stick around for the end to find out about Laika’s wacky battle at Red Dragon Academy!