I've Been Killing Slimes for 300 Years and Maxed Out My Level, Vol. 5 (Manga) by Kisetsu Morita
Following the sage advice of the wise wizard slime Wizy, Azusa and her family continue on their quest to save Falfa from the terrible fate of being stuck as a slime. They must journey across the land to find the great fighting slime Fighsly...When Fighsly refuses to help, there's only one thing Azusa can do-beat Fighsly at it's own game by winning the fighting tournament!