The whole plot is about this 18 years old guy who ends up taking care of some unknown baby. Han Joon Su (Jang Keun Suk) is what we all call a smart ass, rebellious teenager. He doesn't obey anyone and does whatever he wants, be it at school or outside. One day, his parents, getting sick of his attitude, run away. He's completely alright with it and wants to have a party. While shopping, he's found (practically) by a kart which has a baby. There's also a letter with his name, high school and well...he has to take care of his supposed baby and of course, goes through a lot. Even if at the beginning he despises the little devil, he gets accustomed and started to act like...I think it would be wrong to say a dad because he definitely doesn't act like one. But he tries, at least. Another thing is that I laughed but cried at this movie too. Maybe cry is too much but it did touch me. Beyond the movie stands the idea of being a child taking care of a child. Reminds me of Taemin in Shinee's Hello Baby. However, that is actually a common thing in reality. A lot of young people forget what a condom is or simply don't use it because why should they? It's uncomfortable and you can't enjoy it at its fullest. Who cares if there are risks, right? In the end, why should you care about the aftermath? Besides that, there's also a girl who falls in love (or has a crush) on Joon Su and helps him. Also, the baby wasn't his. That just shows that even though he seemed to be the troublemaker, he was responsible.
However, people do what they want and I'm not the one to judge anyone. The idea it's that, Keun Suk as a daddy is adorable :D Now, seriously speaking, having a child is hard so use condoms. No, that's not it. Baby and I is a mix of drama with comedy and it's quite enjoyable to watch. You should totally check it. :)