The distant future. After reaching its peak, Earth's population fell into decline. AI was developed to help preserve the species and manage the ecosystem; a grand experiment in human diversity. Through genetic engineering, a diverse array of peoples, including beastfolk, magical beings, and more, was created to live in a diverse city separated into walled "clusters". Each cluster developed a unique culture, befitting of the people that lived there. Their lives, and the system, is continually maintained by the AI to ensure survival.

This feisty young wizard will stop at nothing to master the spell that saved her life: Explosion! Megumin, the “Greatest Genius of the Crimson Magic Clan,” has chosen to devote her studies to the powerful offensive magic used by her mysterious savior. Then one day, her little sister finds a black kitten in the woods. But this cat isn’t just a new furry friend—she’s the key to awakening a Dark God!

Rentaro Aijo was rejected 100 times in middle school. He visits a shrine and prays for better luck in high school. The God of Love appears and promises that he'll soon meet 100 people he's destined to date. But there's a catch—once destiny introduces someone to him, the two must happily love each other. If they don't, they'll die. What will befall Rentaro and his 100 girlfriends in high school?