Siwon is an unorthodox, self-proclaimed doctor who is easy-going to the point of oozing arrogance. As one of the very few who have passed the 30-year mark in their life, he treats anyone younger as an inexperienced child. At the same time, he will reject being called an "old man", insisting that he's just charming. Siwon likes to keep life in Toshima as pleasant as possible with sarcastic jokes, dorky behaviour and plenty of tough love. His goal is to die of smoking.