According to a report by Daily Sports, the Chunichi Dragons are thinking about introducing red alternate uniforms as way to increase attendance.
The alternate uniforms could be worn at up to seven home games. Fans could also be treated to free replicas during two of those seven games. Other colors, like green and yellow, were considered, but red was ultimately selected because the team wanted something strong/vibrant. It also helped that red is a part of the team's current color scheme.
The last time the Dragons used an alternate uniform was back in 1998 -- they were pin-striped uniforms with a vest top.
Source: Daily Sports 1/10/2013