Tamaki Kasuga harus tinggal bersama dengan nenek selepas ibubapanya ditugaskan di luar negara. Namun, sebab sebenar ketibaannya ialah mewarisi peranan nenek moyangnya, Puteri Tamayori, untuk mematerai pedang Onikirimaru. 5 pemuda berperanan sebagai pelindung sendiri demi menangkis Logos penuh misteri.
Tamaki Kasuga has supposedly gone to live with her grandmother after her parents are transferred overseas. But the real reason for her arrival is that she must continue the role, handed down from her ancestor Princess Tamayori, to seal the sword Onikirimaru. Five young men serve as her guardians against the mysterious Logos.