I've Been Killing Slimes for 300 Years and Maxed Out My Level, Vol. 8 (Light Novel) by Kisetsu Morita
I never set out to be stronger than a goddess, but the power does come in handy when you have to stop a fight between deities. Meanwhile, Sandra hit a growth spurt, (a big one!), we took a trip to a deserted island, and someone I'm pretty sure I've never seen before came to repay a debt?!