Hatsune Mikuo is a popular genderbend character of Hatsune Miku. He is often depicted as either Miku's older brother or her twin. Mikuo was born as a result of extreme down pitching of Miku’s voice, possibly desiring to make Miku sound masculine.
Another beautiful cosplay by Marimo! It’s quite simple yet effective, though I’m not really sure why. Thanks again to Rei for sending this in!