Hoping for a fresh start, househusband Masaki Fujiyoshi, his spouse Hiromu, and their toddler son, Hikari, move to a new neighborhood. The couple's union was frowned upon by many due to Masaki's status as an omega—a secondary gender that allows an individual to give birth. Even for an alpha—seen as the superior secondary gender—such as Hiromu, discrimination seems to be commonplace and a hindrance to a life of domestic bliss. Fortunately, the new family is not alone. Little Hikari becomes attached to Yuuki Hirai, the Fujiyoshis' lonely college student neighbor. Despite his initial reluctance, Yuuki ends up befriending the infant. Moreover, the family can also confide in Hiromu's childhood friend and coworker Tomohiro "Matsu" Matsuo. Although everything is going well for the young couple and their child, a sudden presence from the past might pose a problem for the peaceful life they dream of.

The introduction of 7G Network technology promised miraculous technological advancements; however, the aftermath of its launch plunged Japan into chaos. From drastic changes to the terrain to bizarre mutations among people, the way of life is overwritten with new rules. The town of Agano is one of the few remaining settlements, and its citizens aged 21 and above have transformed into animals. Shizuru Chikura, a high school student from Agano, is desperately searching for her friend, Youka Nakatomi. Coming across a picture in a newspaper placing Youka in Ikebukuro, Shizuru starts packing for a trip. But with public transportation effectively shut down, her options are limited. Fortunately, Tairo Zenjirou, a senile old conductor and the only human adult in town, comes to the rescue when he teaches her how to operate an abandoned train. With her destination set, Shizuru ventures off on a journey to find her missing friend. On the day of departure, however, her other classmates—Nadeshiko Hoshi, Reimi Kuga, and Akira Shinonome—decide to tag along at the last minute as they embark on this one-track adventure that might expose them to dangers far surpassing anything they have encountered in Agano.

When Leoleshea, a dragon god, is accidentally awoken from her sleep within a glacier, she demands this era's very best game player be brought before her. After a year of waiting, she meets Fay Theo Philus, an apostle—a human granted a supernatural ability called an Arise and thus given permission to challenge the gods in games. Fay and Leoleshea realize they share a passion for games, whether it be with cards or a battle of wits with a god. Declaring that she likes this human, Leoleshea allows Fay to call her "Leshea" and team up with her to play in the gods' games. Ever since the gods gave humans the ability to challenge them, they have promised to grant any wish after ten victories. Leshea desires to become an official god again, as she previously descended to the human world and lost her status as a divine being. Fay has only one goal: to find the woman who long ago taught him how to play games. Though Leshea and Fay quickly prove themselves to be a capable team, the gods will not allow them ten victories so easily: every game has its own unique conditions and hidden rules. Together, the duo will have to act as a perfect team to finally achieve their goals.

The story tells the story of a blood-red moon suddenly appearing in the sky, which is known as the red moon event in history. The remaining survivors had to hide in the city protected by high walls. Among the survivors, some people also suffered from mental mutations. Among them, those who could not control their own mental mutations would emit mental plague and radiation. It contaminates the normal people around it and poses a great threat to the surviving humans. In order to solve the source of the pollution, High Wall City established a special pollution cleanup department, recruiting people who can control spiritual energy, and our protagonist Lu Xin is applying for the most dangerous cleanup department!