Tsugunai is the story of Reise, a warrior who has inadvertently angered the Goddess of Light by stealing the mystical Treasure Orb. As punishment, the Goddess of Light forever separates his soul from his body unless he atones for his sins by helping the people of Walondia. Without a physical body of his own, the only way to change the fates of the people is to possess them.

As a member of a mercenary corp known as the Ravens, our silent protagonist Reise is assigned to recover an ancient artifact for a powerful government leader, Lord Cole. This artifact, the Treasure Orb, is cursed. After stealing it from a guarded tower, supernatural forces separate Reise’s spirit from his body. His body winds up in a local monastery, alive but comatose. His spirit is helpless-unable to be seen, unable to speak, unable to interact with the world around him aside from being able to pass through light materials such as wood.

Thankfully, the head monk of this monastery has enough spiritual power to perceive Reise. He informs the mercenary of his strange position, that he has indeed been cursed for stealing the Treasure Orb. The monk then informs him that the only way for his body and spirit to be reunited is through demonstrations of kindness and courage. And in order to do this, he must possess the bodies of others and carry out tasks which they otherwise might not have the strength to do. These tasks range from helping a child find a cat to saving a lost soldier in a treacherous cavern. Thus, Reise heads into the local fishing village to atone for his transgressions.