Bro, if "Korean Movies" is your main keyword, then your Long Tail Keywords will be like "Korean Horror Movies," "Korean Movies List," "Korean Movies 2016", etc. You'll be more specific here. That's all. Kindly search for your keyword on Google and at the bottom you'll find a section called "Searched related to keyword," use them and prepare your keyword strategy. You can use tools like Google AdWords Keyword Planner and pick the best Long Tail Keyword for your website and articles.
RESOURCE: Struggling with Keyword Research? Try this method once!