Because It's The First Time (2015)

With a freewheeling personality, Yoon Tae O is a 20-year-old freshman in college. He has been friends with Han Song Yi since they were little. Now, he begins to have feelings for the girl who has a bright and positive personality. Meanwhile, Tae O has a friend, Seo Ji An, who is well-behaved and exemplary. A love triangle brews between these three people.