The Armed Detective Agency is still on the run from the Hunting Dogs, but not all hope is lost. Detective Ranpo Edogawa has a plan to prove the Agency's innocence and save the world from chaos: to find and capture Kamui—the leader of the terrorist organization Decay of the Angel. In order to determine Kamui's whereabouts, Ranpo and his colleague Atsushi Nakajima must convince Ouchi Fukuchi, the renowned captain of the Hunting Dogs, for amnesty. Although Fukuchi was tasked with arresting the members of the Agency, his past with the Agency's president, Yukichi Fukuzawa, may be the key to earning his trust. But unbeknownst to them, Fukuchi might not be as honorable as he proclaims.

Many years ago, after the end of a bloody world war, mankind took shelter in six city-states that were peaceful and perfect... at least on the surface. However, Shion—an elite resident of the city-state No. 6—gained a new perspective on the world he lives in, thanks to a chance encounter with a mysterious boy, Nezumi. Nezumi turned out to be just one of many who lived in the desolate wasteland beyond the walls of the supposed utopia. But despite knowing that the other boy was a fugitive, Shion decided to take him in for the night and protect him, which resulted in drastic consequences: because of his actions, Shion and his mother lost their status as elites and were relocated elsewhere, and the darker side of the city began to make itself known. Now, a long time after their life-altering first meeting, Shion and Nezumi are finally brought together once again—the former elite and the boy on the run are about to embark on an adventure that will, in time, reveal the shattering secrets of No. 6.

Following an all-out battle with the Paranormal Liberation Front, it is difficult for the people of Japan to continue placing faith in their heroes. To combat the combined power of Tomura Shigaraki and All For One, All Might calls for his ally from the West—the strongest woman on the planet, Star and Stripe. However, All For One decides to intercept Star and her fleet to get his hands on her overpowered quirk before she can enter Japanese airspace. Although Endeavor, Hawks, and Best Jeanist are headed to the rendezvous point, Star makes a gamble in the present to save her comrades.

An evil army is leading a ground invasion against Earth, and their Lieutenant Shun Miller is determined to wreak havoc upon the populace. Miller's ruthless reputation strikes fear even into the hearts of his own subordinates, making him the perfect leader of a charge against a city protected by a powerful magical girl, Byakuya Mimori. However, his attack comes to a halt on the day of their first encounter—because he unexpectedly falls in love with Byakuya at first sight! Overcome by Byakuya's adorably delicate innocence, Miller begins to shower her with gifts and kindness. But Miller soon learns that Byakuya's Angel—the cat-like familiar who turned her into a magical girl—has been exploiting and manipulating her all along. This discovery solidifies Miller's resolve to ensure Byakuya goes on to lead a happier life, but as the war continues, they wonder if their blossoming affection can overcome the reality of their differences.