The Prince of Darkness is missing and the Deadly Sins are being induced into the Universe, overbalancing Darkness over Light. The Guardians find themselves with weaker powers as they struggle to journey to the planet Lusteria where they must battle the sources of the Dead Sins and find the missing Prince. Can they work together and save Lusteria or will the "Light" divide them?

Kouichi lost his memory after he witnessed something he wasn't supposed to see: a murder. Despite suffering from amnesia, the murderer isn't willing to let his only witness go free, even if he is just a child. Can Kouji and his friends protect Kouichi from a heartless killer? And how can Kouji help his twin regain his lost memories when they're too painful to remember?