Monster World IV (モンスターワールドIV) is an action-adventure developed by Westone and published by Sega. It is the sixth instalment in the Wonder Boy/ Monster World series. The game was only released in Japan. As far as I know, Sega had no interest in an international release, since they thought Mega Drive/Genesis would not be needed as the Saturn was about to be released. A fan translation to English was made later, and it was actually picked up and released commercially when to the game was brought to the Virtual Console of the Wii and to the PS3.
You control Asha, the girlfriend of Shion, the hero of the previous game. One day, Asha is standing on a cliff near her home village, and suddenly heard a mysterious voice calling for help. She decides to leave the village and to embark on an adventure to discover the identity of this mysterious person.
The game is an action-adventure similar to Metroidvania games. It has some RPG elements since you can improve your character by finding better equipment and extended the health bar by collecting droplets.