When Dongjun first met Hyeji on a spring day, he just knew she was the girl of his dreams. So he works up the courage to talk to her, and ask for her number-but Hyeji declines, saying if they ever meet again, she will then give him her number. That evening, Dongjun gets a call from his best friend and finds out there was a surprise waiting for him.。主人公の「おしりかじり虫18世(10歳)は、底抜けに明るく元気で歌と踊りが大好き。おしりかじり虫に上手におしりをかじられると、猫背の人は姿勢が良くなり、落ち込んでいる人は笑い出し、自信のない人は自信が湧いてくるなど、見違えるように元気になる。 そんなおしりかじり虫だが、失敗も数知れず・・・。ドタバタな日常シーンに、子どもたちの大好きなユーモアたっぷりのギャグを満載して物語は進行していく。。