In a European city with secret levels buried deep underground, four strangers cross paths while chasing pieces of their own erased pasts. Naoto, an amnesiac swordswoman, teams up with Heine Rammsteiner, a gunman shaped by childhood experiments below the city, while photographer and info broker Badou Nails and ex-assassin Mihai Mihaeroff circle the same buried secrets from other angles. This OVA adapts only select arcs of the Dogs manga rather than the full ongoing series.