重音テト
Kasane Teto (重音テト) is an UTAU character; UTAU is a freeware vocal synthesizer designed for singing. Teto was originally created as a joke of sorts on a forum, but she ended up becoming very popular, even officially recognized by Crypton, and appears in things like the Project DIVA games. Due to her popularity, she is essentially the face of the UTAU program. She is owned by TwinDrill.
リバーシブル・キャンペーン
Reversible Campaign is a song by producer DECO*27, originally made using Hatsune Miku. This outfit is based on how Teto appears in her version, depicted by artist おね美, which you can see here.
This is the shirt collar for the Reversible Campaign Teto top. It's a simple, plain black shirt collar, which you can add onto almost any top. Why not try it out? Furthermore, this collar, the matching shirt, and the tie are all sold separately, so please be mindful of this!