There has been a series of incidents where humans suddenly mummify and die. Jin and K begin investigating with Agent S, who specializes in undercover operations. All the victims had purchased a Chemi-Medic called Shiner 05. The identity of the black box hidden by the company president who developed the product is...?
Ota recalled that during discussions for the second episode, the idea of adding another female character came up. Since both Jin and Elea were shrouded in mystery, that would have left K as the only member of the main cast without any secrets. If most of the main characters were burdened with hidden pasts, it would be difficult to develop the story. Furthermore, rather than having two male agents in the core team, adding a female agent to make it a trio would allow for more dynamic storytelling.
Additionally, since Elea held the key to the overall plot, her backstory couldn't be revealed until the later stages. Taking these factors into account, S was introduced in episode 4.
Producer Yukiko Omote had suggested, "How about writing a story where an enterprise is taken over by invaders?"—so Ota incorporated that premise while making sure the episode also showcased S's capabilities.
To distinguish her from Elea, S was characterized as a combat-oriented figure. Her fondness for chocolate was decided early during the outline stage. At the time, Ota had no idea that Anri Ban, who played S, came from a family that ran a pastry shop. When discussing the episode with director Kenji Suzuki, Ota specifically mentioned, "This chocolate absolutely shouldn't be a standard bar of chocolate." Unexpectedly, Ban’s family ended up creating a custom chocolate specifically for this episode.
While writing episode 4, Ota hadn't initially considered a long-term development for K and S's relationship. The scene where K is deeply concerned about S during her undercover mission was included, but the later developments were left to the preferences of Takeshi Yagi and the other writers. Since the main storyline already revolved around Jin and Elea, K and S’s dynamic was intentionally kept somewhat lighthearted during this two-episode arc.
Regarding the invaded enterprise, Ota initially considered making it an intelligence-trading company. However, since information is intangible, it would have been difficult to convey visually, especially within a 30-minute episode. Instead, the setting was changed to a company selling health supplements via mail order. While exploring ways to depict the unsettling fear of an invisible presence, Ota researched various company names that sounded convincing. Surprisingly, several real-world companies already had similar names, so after much deliberation, the fictional enterprise was named "NANO CYBERTECH," with its product called "Shiner05."
This episode aired in the United States on TOKU on June 6, 2017.
