The makers of Oujisama (warai) are a bunch are a bunch of first class trolls xD
Emperor Tenji) complete with character design and an interview with Konishi Katsuyuki who would supposedly voice him.
Unfortunately for us, it was all a joke. A second interview in which Konishi-san is asked how he felt about being asked to help them with this April Fools joke has also been posted by now.
Apparently he'd really like to join the cast so he asks the readers/listeners to recommend him if they know a good prince for him to voice xD