Len is a Japanese vocaloid published by Crypton Future Media, Inc. He is often seen with Kagamine Rin, who is assumed to be his twin sister. Len and Rin are both voiced by Asami Shimoda.
Len is a 14 year old boy with messy blonde hair and blue eyes. Len and Rin's outfits are similar. He wears a white top with a black collar and a yellow tie. His pants are black with a little bit of gold on them, and he wears baggy black leg warmers and white shoes.
Len is very dorky and likes to joke around a lot. He is clumsy and gullible but fun to hang out with. Normally he has a care-free attitude, but if someone hurts Rin then he will become serious and protective.