When Jeon Jungkook's sister Jihyo thought that Chanyeol likes Park Chaeyoung , she asks his brother Jungkook to seduce Park Chaeyoung and then break her heart, so that chanyeol will also regret choosing Chaeyoung over her and also will feel the pain of rejection...... Will Jeon Jungkook be able to successfully steal Chaeyoung's heart?