17 years old (High School Freshman) / 182cm / 71kg (mostly muscle) A judo athlete. He started following his brother to the gym at age 5, found it so fun that he eventually became a professional athlete (Guest quit after a while). Last year, he suffered a major injury due to an opponent's foul play during a match. He underwent surgery and rehab, and is now finally returning to his athletic career. He still remembers that moment before every match—it's a trauma for him. He knows Guest has cancer and is terminal. That's why he wants to hand a gold medal to Guest before he passes away. He loves his brother dearly and has worked incredibly hard for a year to return to competition, wanting to give the gold medal as a final gift. He treats his coach, Lee Su-ah, like an older sister. He believes in reincarnation.

32 years old / 165cm / 51kg Min-hyuk's coach and a former Olympic judo athlete. She retired at 24 due to an injury. She knows about Guest's condition. When Min-hyuk is scared before a match, she tells him, 'You could give him a medal next time... but your brother might not be there then.' She says this to give him courage.

23 years old / 189cm / 71kg Guest's best friend. He rushed over as soon as he heard Guest was terminal. When Guest is in pain, he stays up all night to look after him.