Harukanaru Toki no Naka de 6

Also known as: 遙かなる時空の中で6, Beyond the Stream of Time 6

by Tooko Mizuno

The manga adapts the game of the same name, and centers on heroine Azusa Takatsuka. Azusa is high school girl who one day finds herself in a world that appears very similar to Japan's Taisho period. She quickly runs into trouble, but is saved by a man named Darius, who calls himself a "demon." (Source: Anime News Network)