Virtual Girl in J-Pop Band?

Several years ago, someone posted a link to a brief YouTube video about a Japanese or Korean girl band, apparently in a television segment there, with four live teen girls and a fifth who, at the end of the video, is revealed to be a computer-generated composite of the other four. I tried the Search function here, but couldn't come up with keywords that worked. (I also manually checked "Hangin' Around" Forum titles without finding it there.)

Does anyone remember the entry or know anything about it (or anything similar)?

Best, Eric