Monster Fishing RPG

The main character and his friend, who live on a country island, leave the island and set off on a journey to catch "Monster Fish" (Mon-Fish) from all over the world. 

During their journey, their friend is eaten by a frog-shaped Monster Fish and taken away! Why was my friend taken away? There was actually a secret...! 
Fishing RPG! Fishing for Monster Fish and saving the world!