More than one hundred years ago, humanity was driven to the brink of extinction by the sudden appearance of the Titans, gigantic humanoid creatures that devour humans with no apparent reason other than instinct. The surviving remnants of the human population retreated behind three concentric rings of massive walls, sacrificing their freedom in exchange for a fragile peace. For a century, these walls kept the Titans at bay, allowing civilization to rebuild in isolation.

This fragile peace is shattered when a Colossal Titan, far larger than any seen before, appears from nowhere and breaches the outermost wall, Wall Maria. As smaller Titans flood through the gap, chaos engulfs the town of Shiganshina. Among those caught in the disaster is a young boy named Eren Yeager, who watches helplessly as his mother is devoured. In that moment, he swears not only to survive but to join the military and exterminate every last Titan.

The live-action television miniseries, titled Attack on Titan: Signal of the Counterattack, serves as a companion piece to the two live-action films released in 2015. Rather than adapting the main story of Eren, Mikasa, and Armin, the series functions as a side chapter that expands the world and develops supporting characters. It begins ten months after the fall of Wall Maria, with humanity struggling to mount a counteroffensive against the Titans but lacking any tactical advantage. The soldiers are desperate for a weapon or strategy that can turn the tide, and hope rests on the eccentric research of Hanji Zoe, a scientist whose obsessive curiosity about Titans has led most of her peers to regard her as unstable.

The first chapter focuses on Hanji as she works to develop the Omni-Directional Mobility Gear, the gas-powered grappling equipment that allows soldiers to maneuver in three dimensions and fight Titans on something approaching even terms. Through a series of experiments and a coincidental turn of events, Hanji refines the gear into humanity's most effective weapon, though her methods remain unorthodox and her obsession with understanding the Titans only deepens.

The second chapter shifts focus to Sasha Blouse, a young woman whose exceptional skill with a bow and arrow is matched only by her single-minded obsession with food. Her backstory is explored, showing the simple hunter's life she led before the Titans breached the wall and how she came to join the military. The story follows her uncovering a mystery involving missing rations, but ultimately serves more to illustrate her quirky personality than to advance any larger plot.

The third chapter introduces original characters not present in the source material. Fukushi and Riru are two rival trainees in the military corps, learning to master the Omni-Directional Mobility Gear. Riru declares she has no interest in any man weaker than herself, prompting Fukushi to prove his worth through combat training. What follows is a tonal departure from the grim desperation of the main story, leaning into slapstick comedy and romantic rivalry as the trainees compete for affection while struggling to stay airborne on their grappling gear. The episode attempts to demonstrate how the mobility gear became the standard for Titan combat by showing its effectiveness when wielders are properly motivated, but the execution shifts dramatically toward lighthearted and goofy territory.

The series stars Satomi Ishihara reprising her role as Hanji from the films, with Nanami Sakuraba as Sasha, Shu Watanabe as Fukushi, and Rina Takeda as Lil. Shinji Higuchi, who directed the live-action films, also directed the television series. The miniseries was released exclusively on the Japanese streaming service dTV in August 2015.