Rikka-Sayuki Theater (???? Natsuyuki Gekijou) is a 10-episode video series released by Yurin Yurin between November 2013 and January 2014 to promote the release of A Kiss For The Petals – Snow White's Knight. These videos take place some time during the middle of the visual novel; their canonical status is unclear.
See Petals' Garden for more information.
In addition to video files with both English and Japanese subtitles, the series has been compiled into a single video you can watch online: