High school girl Hayakawa Yui was sent back in time to 1560 during the Sengoku Period through a time machine built by her younger brother Takeru. She risked her own life to help out the Hagi clan and fell in love with Hagi Kuhachiro Tadakiyo, the heir of the feudal lord Hagi Tadataka.
Tadataka is a typical warlord of the period who believes in winning battles. But his mindset gradually changes because of Yui and Tadakiyo, and he even permits their marriage. Yui is betrothed to Tadakiyo. However, the clan’s arch-enemy Koyama Munetsuru, whom they were supposed to have made peace with, launches yet another battle at the instigation of Oda Nobunaga’s vassal, Ouga Kazunari.
Ouga’s true aim is to make Koyama and Hagi fight and capture the country. Tadakiyo leaves Yui behind and heads to the castle where the advance guard is in order to stop this senseless war. Yui tells his father that Tadakiyo believes it is true victory to live. She escapes from the Hagi clan’s stronghold and goes after him.