- all spectators
- running time
- 117 minutes
- cumulative audience
- 4196859 people
As time passed, she became a 20-year-old young man. However, intelligence is still at the level of a five-year-old. He farts casually in front of strangers, treats his younger brother with respect as if he were a teacher, and when music comes out, he often performs his unique mak-dance. Even though she is a 5-year-old child with impeccable behavior and tone, she still has the best running skills she has been doing since childhood. Kyung-sook sets her goal to 'achieve the sub-three in the Chowon marathon' and concentrates only on her son's training.
One day, ex-famous marathon runner Jung-wook, who had a history of winning first place in a world championship, is ordered to serve as a community service worker while driving drunk and comes to a school in the grassland. Kyung-sook almost begs, and takes over the role of her son's coach to Geor Yi Jeong-wook. Jung-wook thought only of annoying the unknown grassland. However, the more time he spends with Chowon, the more he assimilates into the innocent and honest Jungwon like a child, and Chowon also begins to open his heart to Jung-wook. Although he collapses from exhaustion because he fails to control his speed every time, he discovers the possibility of a marathon sub-three in the grassland, which has exceptional endurance, and begins training in earnest.
Meanwhile, Jung-wook, who looks only insincere, and Kyung-sook, who is not trustworthy, gets into an argument with Jeong-wook one day. Kyung-sook can't respond to Jung-wook's words, "'Don't mistake your child's love and obsession'. Kyung-sook can't shake the thought that she's abusing a child who has never been able to express 'good' or 'dislike' because of his greed, just as Jung-wook said. Kyung-sook feels as if everything she has built up has collapsed. Now, she decides to give up both the marathon and the serve three…