Every 12 years, mercenaries who possess the highest caliber of brute strength, cunning wit, and deadly precision gather to participate in the Zodiac Tournament. Each warrior bears the name and attributes of one of the 12 animals of the Chinese zodiac. With their pride and lives on the line, they engage in vicious combat until only the victor remains. The 12th Zodiac Tournament begins in a desolate city, devoid of any evidence of the half million people who recently lived there. To raise the stakes, each warrior ingests a poisonous gem, thus setting a time limit on the tournament—and on their life. With one wish for the victor up for grabs, the Zodiac Warriors start their cutthroat battle for survival.

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.

Satou Matsuzaka is a beautiful high schooler who has a reputation for being permissive with men. However, a chance encounter with a young girl named Shio Koube makes Satou realize that this is her first and only true feeling of love. Telling others that she lives with her aunt, Satou secretly shares an apartment with Shio. Despite her innocent appearance, Satou is willing to do anything to protect her beloved, resorting to desperate measures to ensure that their happy sugar life remains intact.

A nameless sword wakes up to discover he has been reincarnated from his former life as a human. With his power of telekinesis, he moves around this new world, acquiring several skills and abilities. When the sword comes upon a forest filled with monsters, he meets a young girl fleeing from a beast. Grabbing the sword, the girl easily defeats the monster. After introducing herself as Fran, she names the sword Shishou and officially becomes his wielder. The two set out to become adventurers, but unfortunately for Fran, she is a member of the Black Cat Tribe—a Beastkin group with a bad reputation. No member of this tribe has ever evolved into a mightier beast, but Fran plans to be the first and achieve her parents' dream. As Shishou promises to remain her sword until she attains her goal, they form an unstoppable partnership of impressive strength.