According to Amazon Japan, a short OVA of Hiiro no Kakera
was announced to be released on March 28th. It will be bundled with an illustration fanbook. The title of the OVA is "Totsugeki! Tonari no Ikemenzu" and it will comically reveal the private lives of the five main characters.
Source: Amazon Japan
Hiiro no Kakera: Totsugeki! Tonari no Ikemenzu