Information:
Tatsuya kun and Mayumiinu were brought together to perform the theme song for the Aflac medical insurance product "Aflac shin EVER" in Japan. Though not much information seems to be available on Tatsuya kun (apart from the fact that he's obviously a little boy that was born sometime in the year 2000, since it's been stated that he and Mayumiinu are 31 years apart), Mayumiinu had performed a song previously for an Aflac commercial called "ahiru no Waltz" ("Duck Waltz"). In fact Mayumiinu is known for performing commercial songs, and has performed songs for over 70 commercials.