Kang Mu-gyul is a fictional character from the South Korean television drama series Mary Stayed Out All Night. He is portrayed as a free-spirited and carefree musician who often finds himself in humorous situations. His character is known for his charm and laid-back attitude, which contrasts with the more serious characters in the story. In the series, Kang Mu-gyul becomes romantically involved with the main character, Mary, leading to a love triangle that drives much of the plot. His character development throughout the series explores themes of love, ambition, and personal growth, making him a relatable figure for viewers.