Hakuryuu Izayoi den

Two strange encounter with one unfamiliar name confused Rui. First she unconsciously blurted out when she saw a guy in her school, another time is when she heard a woman cries that unfamiliar name out just right when Rui saw the sword her father who is an archeologist shows it to her. With this sword Rui never know that it could transport her back to the old Japan where her father's troop is having a war with another.

Note: Included in the back of this manga ,there is also an Omake which is a story about Tatsuki and Dule from Maou no Kiza (魔王の刻) This is a prequel story when Tatsuki is still a small kid that doesn't know about his power yet.