Joy, Sadness, Anger, Fear and Disgust are based emotions of human being. Those 5 emotions are the main character in this animation. It happened in the brain of Riley. Every emotion work in the control room and try to fit into various situations. That is the reason why human has different feeling. 

            At first, Riley is a happy kid. She grows in a warm family. That means Joy do her work very well. Everything goes well until one day, her family has to move from Minnesota to Los Angeles, and she gets to the new school. She is excited but it is not easy for young Riley to adjust to the new environment. So, it is problem of this little girl.

           Inside her brain, emotions also have some trouble. Joy and Sadness accidentally lost core memories and spit to another world of Riley memories. There are Anger, Fear and Disgust in the control room. They are trying to make Riley feel good, but it was getting worse because Joy is not there. Riley has ineffable sensations and try to run away from home with the reason "she is missing Minnesota".

           After Joy and Sadness were vacuumed to another place, they were trying to protect core memories and go back to control room. Luckily, Joy never gives up and deal with the problem effectively even Sadness seems hopeless.

           In my opinion, I like Joy who trying hard to go back and make Riley happy, but she always keeps Sadness away. She does not let sadness do his work. When story keeps telling, Joy has learned that Sadness is not the devil. Sometimes, Riley should allow sadness to come out because it can make Riley get through the problems in her life. As a human, we cannot be happy all the time. Variety of feelings is a part of us and negative feeling is not bad after all. You can feel it and do not hurry to feel better :)

           This animation shows that negative emotion is not bad because it protects us from danger, so positive emotion is not good all the time because it will make us careless.