This definitely deserves a 5. The actors played their roles perfectly and the story is superb. It may seem very incomplete since the beginning was not explained (jisoo being bullied at the tunnel was not the beginning, because the black pouch already has money on it which means they are already partners in business). Also, the ending shows so much that you can come up of a thoery, it is either the time how jisoo started his business or it is the beginning of jisoo's life with gyuri somewhere.