Lee Ara is the daughter of Lee Motor and Electronic Companies. Her family is one of the richest families in South Korea but that doesn't stop her from living a normal life. She goes to Seoul High School and is known as the school sweetheart there. Everyone loves her for who she is and not one person takes her for granted, because of Lee Ara, people learn not to take people for granted. She is friends with everyone and has a special memory with her fellow classmates. But the true fun happens with her best friends who are a group of guys called ASTRO. She's been friends with them ever since she moved from Daegu to Seoul for her father's business. It is now their senior year and Ara wants to make it special. But things don't go as planned when her old friend, Kim Mina transfers to Seoul High School and starts to pull ASTRO away from Ara. Not only does ASTRO start to drift apart from her but Ara's ultimate best friend and crush, Moon Bin starts to be closer to Mina. Will high school end the way Ara wants it to be? Or will she have to have to change and adapt to this new situation and find a new ending that will make her happy?