How do you unlock the secret of the lost souls-mini ninjas?

To unlock the secret of the Lost Souls in "Mini Ninjas," players need to collect all the Lost Souls hidden throughout the game. These souls are typically found in various levels, often requiring exploration and overcoming obstacles. Once all Lost Souls are gathered, players can access the secret area or complete special tasks that reveal additional game content. Make sure to defeat any enemies and utilize the unique abilities of each ninja to aid in the search.