A fifteen-year-old boy, Hyungju, accidentally discovers a secret about his birth and sets off on a journey to find his biological father. Through this journey, he comes to understand both the father who gave him life and the father who raised him, as well as gaining insight into himself. The boy learns the true meaning of fatherhood and fully accepts himself, leading to his growth and maturity.

Mathematicians try to solve everything with math. They believe that even life can be explained through mathematical theories. Hyungju, who has been receiving education as a math prodigy since childhood, tries to define his identity entirely through DNA, probability, and numbers. However, his life and journey do not unfold like a mathematical formula. Numerous variables interfere in Hyungju's life, leading to an unpredictable journey. Throughout this process, he realizes that there are many things that cannot be proven by math alone. The fifteen-year-old boy learns through his challenging journey that the equation of life is far more complex and beautiful than math.

- CHOI Chang-hwan