Most of the monsters in the story come from the monster picture collections "One Hundred Demons Night Parade" by Toriyama Sekien and "One Hundred Stories of Little People" by Takehara Shunzumi. Nura Rikuo appears to be an ordinary 13-year-old first-grade student, but in fact he is the grandson of the monster "Nura Oni" and has a quarter of monster blood. He is an ordinary boy during the day and a monster at night. When he was a child, he admired his grandfather very much and liked the "Nura Group" under his grandfather very much. Because his father Nura Koiban died a long time ago, Rikuo, who should have inherited the third generation of "Nura Group", refused to inherit because he did not want to become a monster that his classmates feared and hated. Until one day, the monster Gangoji who wanted to become Nura Oni attacked the school bus that Rikuo and his classmates were riding in order to retaliate against the Nura family. Rikuo, who was eager to ask for help, instinctively summoned the monster bloodline and rescued his classmates. Will he choose to become a monster in the end?