The chubby girl in the middle of the stage is Naomi Watanabe, one of the most popular Japanese female comedian at the moment. Many people like her Instagram as she uploads lots of interesting photos.
She is also famous for copying Beyonce. You can see her dancing brilliantly in the video below, although she is not singing.
You may like to start at about 6 minutes 35 seconds as she dances with Uptown Funk by Bruno Mars.