This is the fourth volume of the I've Been Killing Slimes for 300 Years and Maxed Out My Level manga. It was released on April 12th, 2019, and collects chapters 20-25 of the manga.
Contrary to their menacing reputation, the demons wish to reward Azusa with a medal of honor for managing to broker a peace treaty between the Red and Blue dragons, which has brought a long-sought-after stability to the region.
With Beelzebub at the helm, the group sets out for the ceremony atop the majestic Leviathan, something reserved for only the most esteemed guests of the Demon Kingdom.
Unfortunately for them, Halkara's clumsy demeanor and oafishness causes a major political incident soon after they arrive, and Azusa is brought into direct conflict with the ruler of the Demon Kingdom, the Demon King, with the lives of her family and friends hanging in the balance.
- Chapter 20 - Let's Meet the Demon King
- Chapter 21 - Infiltrate the Demon Castle!
- Chapter 22 - Battle vs the Demon King
- Chapter 23 - The Medal Ceremony and the Second Dragon
- Chapter 24 - The Cookie Bake-Off
- Chapter 25 - My Daughter Is Stuck as a Slime