After the end of "Kiniro no Corda 10th Birthday," the 10th anniversary fan event of the visual novel series "Kiniro no Corda", the manager of Uchida Yuuya, who voiced two roles in the series, tweeted that near the end of last day's event on September 8th, an announcement would be made that the most recent game of the series "Kiniro no Corda 3" (released February 2010) will be animated.

Previously, the first game and part of the second game were animated in a 2-cour 26-episode TV series in October 2006 and 2-episode TV special in March 2009. However, unlike the first two games, "Kiniro no Corda 3" shares no common characters with its two predecessors. It is not yet known whether it will be a TV series, and no schedule, staff, or cast information is available yet.

Source: Uchida Yuuya's manager's tweet

Edit: It is now confirmed to be a TV series starting April 2014.

Source: Official anime website

Kiniro no Corda 3 on MAL