In the heart of Tokyo's bustling Hanamachi district lies Kurogane Ink, a tattoo studio where tradition meets modernity. Owned by the gifted tattoo artist Mai Kurogane, the studio is a sanctuary of intricate designs and serene concentration. Mai's life takes an unexpected turn when Detective Sato Hayashi seeks her help to investigate a series of art thefts linked to the Yakuza.

Mai, who prefers to stay out of police matters, is drawn into the investigation when she learns that the stolen artworks are connected to her mysterious past. The Yakuza's symbol, a phoenix that matches the tattoo on her back, is found on the stolen pieces. With a shared goal of uncovering the truth, Mai and Sato form a reluctant partnership.

Their journey takes them through the shadowy underworld of Tokyo, from high-stakes auctions to dangerous confrontations with the Yakuza. As they delve deeper, they uncover a conspiracy involving ancient artifacts and a secret collection linked to Mai's heritage. Each step brings them closer to the heart of the Yakuza's operations and the secrets of Mai's past.

Amidst high-tech espionage and perilous confrontations, Mai and Sato navigate their growing partnership, uncover hidden enemies, and protect Tokyo's cultural heritage. Their quest for justice is a thrilling blend of mystery, danger, and the art of tattooing, set against the vibrant backdrop of Tokyo's streets.