According to Nitro+, a short OVA will be bundled with PC adventure game "Guilty Crown Lost Christmas", which will describe the prequel to Guilty Crown. It's 12 minutes long and will be released in May 31st.
In 2029, Scrooge escapes from a research facility, where he had been confined as an experimental subject. His body was remodeled by genetic manipulations and he uses his psychic power to kill the chasers. One day, he meets another experimental subject called Carol. When three psychic chasers hunt down the two, Carol asks Scrooge to use his right arm to extract a weapon from her body.