WARNING: The following contains spoilers for 86-Eighty-Six Episode 5, “I'm With You,” now streaming on Crunchyroll.
Episode 5 is the 86-Eighty-Six anime's first to truly match the intensity and horror of the light novels. As more crucial details about Shin's past slip out, the true nature of the autonomous Legion machines is made horrifically clear – as is Shin's mental connection to them.
In the wake of Episode 4's revelation that Major Vladlilena Milize knows Shin's older brother Shourei, Episode 5 reveals exactly how the two met. Years ago, Lena's father Vaclav took her by plane to the edge of the battlefield so she could see the full scale of the 86's plight in person. However, their plane was shot down by a Legion mecha. Vaclav was killed in the crash, but “Rei” rescued Lena.
In the present day, Rei has been dead for years – killed in the line of duty – but his story hasn't yet ended. When Lena asks Shin what happened to Rei, Shin confirms his death – but says he's still searching for his brother. He isn't referring to Rei's body or remains, however, but something far more disturbing.
The Republic of San Magnolia has always believed the Legion are simply autonomous machines that, despite killing their own human creators, will automatically shut down in around two years' time. In their eyes, as long as they keep forcing the 86 to fight for them, the world will be safe again soon. But the 86's latest battle against the Legion reveals a new model called the Black Sheep, machines that command and strategize from afar. How can they do this? Just before they kill a human fighter, the Black Sheep makes a copy of his or her brain and plays their traumatic last words on repeat. In other words, some Legion effectively carry the “ghost” of a human inside them.
The scope and horror of this process are laid bare when Shin warns Lena to cut off her Para-Raid access before the battle begins. Shin, who once came very close to dying, knows the Legion's movements ahead of time because he can hear the terrifying screams of every single dead human inside a Black Sheep's system. This explains why he's so stoic and emotionless despite all the trauma he endures: he has no other choice.
Shin and the rest of the Spearhead Squadron fight off the new wave of Legion attackers without suffering any significant losses, but the experience is especially traumatic for Lena. Always determined to help her soldiers out however possible, she ignores Shin's warning to shut off her Para-Raid and therefore hears and feels what Shin does on the battlefield. It's a stunning sequence to watch: intense piano keys and violins play in the background while on-screen, Lena shuts her eyes and screams in agony as she hears a number of dead 86's final screams – including Kaie's last words “I don't want to die.” Lena now understands what Shin has endured every single day for the last several years. It's a wonder how he hasn't gone mad.
How does this all connect to Rei? It's not fully clear yet, but Episode 5 does provide hints. Despite having died years ago, Shin still searches for him. Like all the 86 of today, Rei was persecuted for his lineage and skin color and forced to fight against the Legion, presumably having died on the battlefield. A quick flashback scene shows a younger Shin being choked close to death, and he still has a deep scar on his neck. Put all of this together and it suggests that Rei's mind was copied and put into a Black Sheep, where he now commands large forces of the Legion. Whatever happened in their past, Shin desires revenge for it by finding and killing the ghost of his brother.
Along with Shin's personal motivations, 86-Eighty-Six makes it brutally clear just how dire the 86's – and by extension the grotesquely privileged Republic citizens' – situation is. With the ability to copy dead humans' brains and operate just as strategically as human soldiers, they will not simply shut down in two years. They are here to stay, and the number of sacrificial 86 lessens by the day. Unless the Republic sees the many errors of its ways, and fast, the entire world looks doomed.