Kagamine Rin & Len

Kagamine Rin & Len (鏡音リン・レン), codenamed CV02, are Japanese VOCALOIDs developed and distributed by Crypton Future Media, Inc., and were initially released in December 2007 for the VOCALOID2 engine. They are the second set of vocals for Crypton's Character Vocal Series and are both Character Voice VOCALOIDs. There have since been numerous installments such as additional voice banks dubbed 'Append', an update to the VOCALOID4 engine, and an English vocal.

Their voices are provided by the Japanese voice actress, stage actress, and singer Asami Shimoda (下田麻美 Shimoda Asami).

Etymology
Their given names of Rin and Len were said to be based on "right" and "left" according to Asami Shimoda. She later confirmed in an interview after the Append release that the names were based on Ken and Rin from Hokuto no Ken, derived from a discussion about names that were familiar from her childhood.

Their surname was derived from the developing code combining Kagami (鏡, mirror) and Ne (音, sound). This refers to an "echo", which is a sound being bounced back to the user from a different direction caused by soundwaves hitting a surface at a direction that reflects it back the way it came.