Akanesasu Sekai de Kimi to Utau

One day, guided by a peculiar voice, our heroine is suddenly thrust into a different dimension. She has landed in a parallel world called ‘Hinomoto’ where many historical figures live.

'Hinomoto' was once a land which was blessed by the sun. However, when the sun stopped rising the land became a region of Polar Nights. At such a time, beings called ‘Shikigami’ started appearing suddenly, spiriting people away. The people struggling against the Shikigami prayed for the arrival of their Priestess.

Our heroine was guided by a messenger of the Moon Goddess, Tsukuyomi, as the priestess tasked to find the ‘Norito’, an invocation to awaken the sun.

[From Fandom]