nano, also known as PENICILLIN nano, was formed in 2006 by PENICILLIN vocalist HAKUEI and guitarist CHISATO. Although the two have had other solo-activities in the past, this was the first time that they worked together on a project other than PENICILLIN. Their name was chosen as a wink to the iPod Nano, which was popular in Japan at the time.
In June 2006, the band was invited to perform at the American convention AKON in Texas. As well as a performance, the duo held a Q&A session in which they revealed the project would only be short-lived so that they could return and continue with PENICILLIN’s activities. Since nano was only going to be active for a limited time, they performed a vigorous schedule.
Within those few months they also released seven singles, which were released one day after each other. They concluded the series with the release of an album, unborn child’s dream. Each single contained two tracks: a cover of a PENICILLIN song and an original nano song. There were two versions of each single: one with a CD and another with CD+DVD. The DVDs contained short films, a "chapter" per se, and when all of the DVDs were combined they formed an entire film.
After their burst of activity, the unit ended its activities. They did, however, make a re-appearance in 2010 when they performed at a PENICILLIN fan club event.
