嬉しい、楽しい、幸せカーニバル。 (Ureshii, Tanoshii, Shiawase Carnival.)

Background
This song was uploaded onto Niconico and YouTube on December 17, 2014. It's part of Utata-P's Happiness Series and the sequel to Eien ni Shiawase ni Naru Houhou, Mitsuke Mashita.