Imaichi-tan (Masisi edit) is available on Masisi's website. Imaichi-tan is an Internet meme spawned from a job-placement ad. Any commercial use of this model is strictly forbidden.
A modified version with extra expressions by Shabel-P is also available as well as a chibi version.
Many Western users unfamiliar with Imaichi-tan have mistaken her for a bizarre version of Miku Hatsune. The unusual design is intentional, as the prompt for the ad was, "What is this girl missing?" and her name translates to "Girl Who Lacks Moe."