We set our scene in the Meiji era.

Having lost her grandmother, Shirafuji Sana found herself completely alone. With nowhere else to go and nothing to eat, she turned to the Imperial Army and its strange 'bride thorn' program.

Bride thorns are girls offered up as rations to the Vampdolls - blood-drinking women conscripted into the Army as its fiercest soldiers. Starved, desperate and completely unaware, Sana was made to sign an enlistment contract, only to be promptly introduced to Hanafusa Yukine, a beautiful, yet scornful Vampdoll.

At first, the two were far from an ideal match. With time, however, little by little, they began opening their hearts to one another. On their first night, they learned just how exhilarating - physically, emotionally - sucking blood can be. This came as a shock, but the two, awkwardly, trustingly, successfully made it through their first feeding.

Not long after that, they were sent out for active service and Yukine was incapacitated in the fighting...

[Translated from the official description]