AtHeart's digital single "Butterfly Doors," which came out on March 11, has been a big hit. For seven days in a row, it has been at the top of the YouTube Korea Daily Popular Music Video Chart. The music video has been watched over 22 million times as of April 04. It debuted at number 16 on March 26 and stayed there, showing that it will continue to be popular. This success is due to the song's complex sound and stylish performance.
AtHeart shows off their impressive stage presence with difficult choreography that is based on strong fundamentals. The group has gotten great reviews from fans both in the United States and other countries, and they've stood out on music shows and other online content. The visuals draw attention to how unique each member is, which makes them even more appealing. Notably, web content that showed member Nahyun with Belly Bear got a lot of attention and was seen over 310,000 times. Online users who liked her said nice things about her looks, praising how fresh she looked and comparing her to first love.