The Blade of a God (Hestia Knife).
Flashbacks show how Bell decided to become an adventurer after his grandfather was killed by a monster, eventually meeting Hestia and becoming her Familia. The God Ganesha, whose arena the gorilla was freed from orders it recaptured before it harms innocent people, even asking other Familia for help. Hestia eventually finds her way back to Bell and they flee the Gorilla together. Hestia gives Bell the Tanto she names the Hestia Knife, a living weapon enchanted to grow more powerful the stronger Bell becomes...