John Steinbeck/Synopsis

The Guild Arc
Steinbeck first appears where he's shown on the ground after crashing his truck, then complaining about the country's narrow roads. After getting up, he talks with Lovecraft about a "package" about to be delivered. Sometime later, he shows up with his partner in the middle of the conflict between the Armed Detective Agency and the Port Mafia, warning them about the arrival of the package (which is nothing more than ability users from the Guild). After wiping out both factions, he retires with the rest of his partners.

Later, he is seen together with Fitzgerald in a cruiser, commenting about the situation and spending time with him.

John shows up later in the countryside together with Lovecraft after accepting the Mafia's proposal to capture the clerks from the Armed Detective Agency as bait, even though they knew it was obviously a trap. They are seen waiting to ambush the clerks, where he then activates his ability in order to capture them. The clerks attempt to escape by car via another route, but due to the propagation of his ability, the car is caught easily. There, he has a small conversation with Naomi, revealing information about his ability and himself. But thanks to this, he loses precious time and gets surprised by Kunikida and Tanizaki, whom he then engages in combat. He loses the battle and is stripped of his vines.

Thanks to the time bought by Lovecraft, he is able to stand once again and make use of his ability, catching the clerks once more. He then has a small talk with Tanizaki. During the conversation, he notices a single truck drifting off its lane thanks to Light Snow. Having no time to react, the vehicle crashes into him and Lovecraft. It's discovered that they survived, but just as they are about to resume the pursuit, they get arrested by the police.

In an abandoned building, Steinbeck visits the restrained Kyūsaku Yumeno, who suffers relentless torture and pain thanks to Steinbeck's grapevines that writhe through Q's body. Though Steinbeck names their tactician to be behind the emergency plan, he also blames Q for attempting to mess with Lovecraft that led to their abduction. He explains how the emergency plan works: he has connected his grapevines to all of Yokohama's trees, and the pain and harm inflicted by the citizens on the the trees are transmitted to the grapevines that restrain Q. As such, anyone harming trees and other flora harms Q and receives their curse.

At their breaking point, Q bursts into tears, lamenting their misery. They never asked for their ability, and they do not understand why bad things always happen to them. Steinbeck indifferently explains that Q suffers simply because they were born as themself, and even though God exists, He does not love them. The exchange ultimately breaks Q, who activates Dogra Magra's curse.

After the incident, Steinbeck, Lovecraft, and Guild operatives ambush Dazai who has come to rescue Q. However, Chūya Nakahara makes an unexpected appearance and overwhelms the armed forces. As Steinbeck tries to retaliate, Dazai and Chūya easily subdue him. He is later asked by Dazai at knifepoint regarding Lovecraft's eldritch form. Steinbeck refuses to spill any intel to him, but Dazai sees through his words and thwarts Lovecraft together with Chūya's Corruption, ultimately resulting in their defeat and Q's rescue.

After evacuating the Moby Dick, an injured Steinbeck awaits for Twain and a captured Lucy Maud Montgomery out of a helicopter after she helped Atsushi escape. Steinbeck commends her courage in betraying the Guild, though he muses how her bravery was short-lived after his grapevines effectively subdued her ability. He then turns to Louisa and asks for their next course of action. Later, he leaves together with Twain, Louisa, and Lucy to avoid getting caught in the fall of Moby Dick.

Following Fitzgerald's defeat, Steinbeck and the other Guild members discuss the fate of the organization. Though Twain thinks that it is high time to accept their organization's end, Steinbeck advises them that their lives have not ended. He then decides to stay and pacify the internal rebellion among the remaining Guild forces, much to Twain's surprise. He admits that he harbors a hatred towards Fitzgerald and his manipulative attitude, but he also knows full well that he must do what it takes to save his family.

The group then encounters Lovecraft, who mutters about his finished "contract" before jumping off the ocean to sleep. In the anime, Twain wonders what Lovecraft really is, to which Steinbeck remarks that he was one of his few friends.

The Guild Aftermath Arc
During Fitzgerald's comeback, an infuriated Steinbeck observes through his grapevines how Fitzgerald and Louisa mark the birth of a renewed Guild. As interim leader of the surviving Guild forces, Steinbeck plans to crush Fitzgerald's ambitions, anticipating to befriend his former leader when the latter learns to never stand back up again.