Plot

A rebellious high school student sees his life take a strange turn when he goes to the grocery store and someone leaves a baby in his shopping cart, along with a note claiming he's the father.

Joon-soo (Jang Geun-suk), and his life when he becomes a student father. Han Joon-su is a tough 18 year old high school kid that loves to cause trouble. He often gets in gang fights, once with 17 other guys, but always comes out as the victor. Then one day Joon-su's parents have decided to go out of town as a way of discipline to their rebellious son. Instead of feeling terrible and lonesome, a party is called over their mansion. He goes shopping and comes upon an unexpected surprise- a little toddler sitting in a shopping basket wearing the name tag "Han Wooram" and points to Joon-soo as his father! Still puzzled, he takes the baby home and thereon starts his adventures in trying to be the best father he could become—Wikipedia