A Tithe in Blood

As a reserved and unassuming university student in snow-bitten Hokkaido, the personal tragedy which visited Honoka Asakawa would lead to her experimentation in a magical art thought long-lost — blood magic. Unexpectedly able to visit the sealed world of Meiji-era Sapporo, Honoka's quickly taken under the wing of the cheerful and bright Lady Yasue, a powerful mage who's remained in this gilded cage for a century.

As their feelings for each other develop, the true repercussions of Honoka's first steps into the secret world of magic and mages are only just starting to play out, eventually leading to catastrophic consequences.

[From Steam]