Currently, there has been no official word explaining the name "MAYU."
The rabbit she is holding is named Usano Mimi (宇佐乃ミミ). The name translates to "bunny ears." It was first introduced as an April Fools' Day 2012 joke as a parody of the Crypton Future Media Character Vocal series website. There, it was listed as a new line of VOCALOIDs called "Animaloid."
MAYU's design is based on gothic lolita fashion. Her hair itself fades from a light blonde to rainbow, and she is depicted with a hat that has a speaker attached. Her earrings appear to be styled like in-ear headphones that hook over the ear. The buttons on her dress are amplifier buttons/knobs, while the bottom of her dress has a keyboard pattern. Her shoes also have neon-lighting.
She holds an axe, which is to show her yandere influence. She also holds a rabbit doll which has a microphone at the top of its head. When she holds it up to sing, she grabs it by the neck, as if she were strangling it.
As part of her promotion, EXIT TUNES released MAYU as a special package, which features her VOCALOID3 voicebank and a Special 2-disc CD. This bundle also comes with a MAYU cellphone strap and mouse pad, though note that these items are limited stock. MAYU also has several pieces of merchandise based on her.
Due to early announcement, MAYU started to gain popularity several months before her release. At the release date, she had 880 artworks on DeviantArt. This is slightly above galaco level, while also being slightly below CUL and Aoki Lapis, and noticeably less than IA.
In Japan, due to EXIT TUNES' effort, she received more attention. MAYU songs appeared in the Weekly VOCALOID Ranking seven weeks before her release. By the release date, her most popular song had earned 330,000 views on NicoNicoDouga, and had hit the #1 position in the Ranking (but only for one week). By that date, she had six songs with 50,000-150,000 views, and seven songs with 10,000-50,000 views. However, due to her heavy promotion, this result is not spectacular. Moreover, some of her promotional songs reached a lower number of views for their famous producers. Therefore, MAYU's final level of popularity is not exactly clear.
In Feburary 2014, Vocaloid Otaku user "Dessert>desert" decided to run a test to see how many illegal Vocaloid downloads had been made via torrent. At 11,404, Mayu was the second highest download, beaten by 12,434 illegal downloads for the VY2v3 package.