Joonwoo Choi hates school and has trouble making friends. The only time he's happy is when he's talking to strangers on the phone app Random Chatting. That's how Joonwoo befriends a girl on RanChat who happens to be his classmate Yoon Sungah, but she has no idea about it! Will Joonwoo be able to fight his social anxiety and get closer to her in real life? 랜덤채팅의 그녀!