18-year-old Shinogi Inumata has no job, no dreams, and no will to live. One day, on his way back from yet another failed job interview, he encounters a mysterious beauty who appears to be a malicious spirit — Jelknacht Finsternis. Her demand is simple, yet terrifying: “Marry me, or die here and now.” Suddenly dragged into a battle against humanity’s enemies — the Highlanders, agents of the gods — Shinogi must fight for survival and salvation. With Jelknacht, his overwhelmingly powerful and emotionally stoic (yet secretly doting) new bride at his side, he’s destined to become the savior of the world!? Thus begins a battle fantasy overflowing with affection from the strongest cool-dere bride!