Kagamine Rin & Len (Japanese: 鏡音リン・レン), officially code-named CV02,[1][2] are a pair of Vocaloid software voicebanks developed by Crypton Future Media, headquartered in Sapporo, Japan.

Their official moe anthropomorphism consists of a pair of twin 14 year old singers, a boy and a girl, respectively named Len and Rin.

Their official code name, CV02, refers to their position as the second Vocaloids made by Crypton Future Media for their "Character Vocal Series" (abbreviated "CV Series"), succeeding Hatsune Miku (code-named CV01) and preceding Megurine Luka (code-named CV03).

Initially, only Rin’s concept art was made public, and Len was conceptualised subsequently.

[5] They received mixed results from producers because compared to Hatsune Miku, they were considered much harder vocals to use.

Asami Shimoda noted that she often received comments from Vocaloid fans that Rin's voice echoes within their heads and makes them feel dizzy, while Len's higher ranges were not favored by those not fond of the pair entirely.

[12] During development, Crypton's initial concept was to make a pair of female and male vocals.

The first idea of this concept was twin voices of a girl and her mirror image of opposite gender.

Crypton Future Media had the intention to distribute them as twins, but this idea was not adopted and their relationship was left unconfirmed.

[13] After seeing many works that depict their relationships differently, Crypton announced on a magazine interview that those would meet their ideal.