Kagamine Rin & Len

Kagamine Rin & Len (鏡音リン ・レン) were released December 27th 2007. They are part of the Vocaloid2 Character Vocal Series developed by Crypton Future Media Ltd. (CFM). Their product contains a male voice (Len) and a female voice (Rin).

KEI was given a concept by Crypton that included Rin and Len's approximate ages, as well as the idea of them being 'mirror images' and, like Miku, androids. Kei was not given any further direction due to his experience gained from illustrating Miku. Rin was the first one to be illustrated and Len was made to match her, following Crypton's concept. Their leg features are designed to mimic speakers.[1][2] The keytar Len is often featured holding in merchandise, a Yamaha KX5 – from which both the Kagamine designs take certain design elements from.

As they were under development, Crypton had the concept of making a pair of male and female voicebanks. The first idea was for two voices of a girl and her mirror image of the opposite gender, just like twins. [3]

CFM had an intention to distribute them as twins, but this was not adopted either. After seeing many works that depict their relationships differently, Crypton announced in a magazine interview that those would meet their ideal. However, Crypton's final announcement was that they were neither siblings nor lovers. [4][5] During Append production, Wat described them as having one soul between the two of them.[6] During the boxart for the Append, Wat described it as making the pair seem like twins,[7] due to the fetal position they were in.[8]

For their appends, Wat wanted them to have a sense of transparency about their design.[9] In clarification to what he meant by this, he stated the "transparency" was in reference to their hearts.[10]

The Kagamine's were marketed as a "2 vocals for the price of 1" package, and aimed to catch the interest of the growing Vocaloid fandom. Unlike Hatsune Miku, they were not an immediate hit, failing to meet marketing expectations despite receiving the same level of promotion as Miku was receiving at the time of their release. After the release of "Act2" sales picked up steadily and they became one of the more heavily market Vocaloids, though have never met the marketing strength Miku gained before them.

They were slow to gain popularity in the Japanese fandom after the backlash from their original voicebanks, and although they have 2nd highest number of songs combined, they are not as popular as Hatsune Miku. Their designs have also spawned many producer based derivatives.

In the Japanese fandom, Rin is the more popular of the two Vocaloids with more related works than her counterpart Len. Part of the problem in the Japanese fandom was owed to the backlash from Kaito's failure, male voicebanks had little demand at that time and Len's voicebank was left as the only male Vocaloid 2 vocal until Gakupo's release, and was not used as often as Rin's voicebank.[20]

A independent Vocaloid search on Nico Nico Douga revealed that most Vocaloids had less than 1,000 videos uploaded on Nico Nico Douga in between July 1 and December 15 2011. The Kagamines, however had managed to gain enough views not to fall into this category. Rin received 2811 uploads while Len received 2021. Rin had the 3rd highest total views during this period of any Vocaloid with 5,327,456 views and 477,046 mylists, and Len managed 4,555,580 views and 413,901 mylists. When sorted by average, Len was third with 2254.12 views per video, and 204.8 mylists, (which was more than Miku’s) and Rin’s was 1895.22/169.71 mylists. However, when the views were based on the more accurate mean total, Len and Rin achieved 355 views/16 mylists and 349 views/16 mylists respectively per video coming bottom of the top 6 Vocaloids. However, the Kagamine software was the only Vocaloid package to be be in all top 6 lists besides Gumi.[21]

Their Append outsold the Miku Append during the period after their release. The Act2 package and Append secured 4th and 5th spot between them in Crypton's end of year top 10 Vocaloid sales despite only being released for a short period of time (mostly owed, but not entirely, to pre-orders).[22][23][24] However, they did not maintain this, in June 2011, their Append had fallen to 8th place, one below Kaito's Vocaloid voicebank.