How can you unlock ruin 5 in the ruins in epic battle fantasy 3?

To unlock Ruin 5 in Epic Battle Fantasy 3, you need to complete the previous ruins and ensure you have defeated the necessary bosses leading up to it. Specifically, you must have defeated the final boss of Ruin 4. Once you've accomplished this, you can access Ruin 5 from the main ruins hub in the game. Make sure to check for any specific requirements or quests that might need completion as well.