Jun'ichirō Tanizaki/Synopsis

Armed Detective Agency vs. Port Mafia Arc
Tanizaki poses as a hostile enemy with a grudge against the Agency, threatening to bomb everyone and having his sister pose as a hostage. This charade acts as Atsushi Nakajima's entrance exam into the Agency.

After the incident, Tanizaki apologized to Atsushi, saying that even if it was for Atsushi's exam, he was still rude to him. This fact shows off how much of a caring person Tanizaki can be. It was also when he had told Atsushi that he too worked as an assistant of sorts at the agency.

He and Naomi later attend Atsushi's first major mission, assisting a woman claiming to be stalked. The mission ends in an ambush orchestrated by Port Mafia, and the woman violently shoots at the trio. Naomi saves Tanizaki's life by using herself as a shield. Naomi's dire state makes Tanizaki snap, and he uses Light Snow to counter Higuchi's assault. Just as he's about to crush her neck, Ryunosuke Akutagawa uses Rashomon, which severely injures Tanizaki, leaving Atsushi on his own against Port Mafia's hellhound.

With the help of Akiko Yosano's ability, Tanizaki makes a full recovery. As they struggle with Port Mafia goes on, he investigates one of the cargo ship areas during the Agency's rescue mission for Atsushi, only to find all crew members slaughtered by Akutagawa. Thankfully, Atsushi defeats the latter. In the aftermath, Tanizaki is among the members welcoming their newest member to the team.

The Guild Arc
This peace is short-lived. Following Port Mafia's failed kidnapping, The Guild makes its move to obtain Atsushi themselves. Once more accompanying Atsushi with his sister to investigate Kenji's disappearance, the trio breaks when Lucy's ability traps Naomi. A panicked Tanizaki tracks Lucy down, but she quickly traps much of the public in her ability. Despite his ruthless desire to save Naomi, Tanizaki also falls victim to Lucy's ability. However, Light Snow creates a false door, tricking Lucy. Together with Atsushi, Tanizaki succeeds in freeing Naomi and Kenji. Later on, Tanizaki uses Light Snow to hide the helicopter he pilots to give Atsushi cover so he can board Moby Dick and defeat Fitzgerald once and for all.

After the Guild incident, Fyodor makes his move using a mysterious ability-user assassin that allows Pushkin to infect both Mori and Fukuzawa. Once it becomes unavoidable that one of the infected must die to save the other, the Port Mafia and Agency enter yet another heated war to save their respective leaders. Tanizaki personally goes to where Mori lies unconscious and helpless thanks to the disease, but Koyo stops him and nearly injures him. Soon the struggle seemingly ends in Port Mafia's favor, having caught Tanizaki, but Tanizaki's spirit remains unbroken and unfazed, unsettling the executive members a great deal.