When childhood friends Yui and Naoki are by chance reunited as adults, they begin to feel they were destined for each other. However, just as Naoki prepares to propose to Yui, he becomes embroiled in a mysterious incident and dies. Now Naoki's soul wanders the world unable to express his true feelings for Yui. Yuzuru, a detective and the only person who can see Naoki, goes in pursuit of the truth behind Naoki’s death. At Naoki tries to use Yuzuru to talk to Yui, but will he be able to convey his message of love?
Niina Masayoshi is the leader of DCU. The group was newly created by the Japan Coast Guard and stands for Deep Crime Unit. Their mission is to find evidence and dead bodies hidden underwater, that are crucial to solving criminal cases. Niina Masayoshi never gives up investigating the truth.