Tenth‑grade student Kai To Damon is a typical hooligan genius; in his life he cares not about academic achievements but only about solving riddles and puzzles. Kai would never have gone to school, except that his childhood friend Nonoha Ito—a sporty and energetic girl—has taken on the entire burden of caring for the "unruly" one. However, the academy "Square Root" itself is strange; it"s full of puzzle lovers, and Soji Jikukawa, president of the student council and puzzle club, managed to stump even Damon himself. Taking the boy "softly," the cunning Soji sent him into a deadly labyrinth, which Kai traversed with Nonoha"s help; he received the "Orpheus contract"—a device that allows one to fully harness the brain"s potential, called "phi brain." Now Kai is one of the Solvers, a few chosen ones capable of handling the schemes of a worldwide secret organization that invents ever more unsolvable puzzles. Under the combat pseudonym Einstein and in company with loyal Nonoha (where do you get her?), the main character begins life in an environment that does not recognize loud words and inflated authority. One must earn a place in the Solvers" hierarchy by proving oneself, cracking new puzzles like nuts and getting closer to the "mystery of God." And why all this is needed by the school director and the ominous world backstage—perhaps the biggest mystery of the series!