Hatsune Miku does not have a brother as far as officials say. If Miku does have any brothers, it is most likely that you saw a fanmade. Sometimes the Vocaloid product line (E.g. Miku, Rin, Len, Luka etc) is regarded as being a family.
- The following may be
- Hatsune Mikuo (初音ミクオ) - A genderswap of Miku created by the fandom, his design is similar to Miku, only he has short hair and wears pants.