I've Been Killing Slimes for 300 Years and Maxed Out My Level, Vol. 15: Volume 15

I've been killing slimes for 300 years, and my family has finally decided on my birthday! We didn't have a date until now (mainly because I forgot it...), but my daughters are going to celebrate it with me this year, and I'm really, really excited! Later, I meet the goddess of fate (I can't be surprised anymore!), I help out a phantom thief (and my family grows), and I visit a strange land where there are no slimes! I'll share another short story from a drama CD at the end, so don't miss it!