Konjiki no Gash!! Gaiden: Friend
The story in this one-shot takes place sometime after the original ending, and focuses on Gash's feelings towards his current life as the Demon King, and also on his deep bond with Kiyomaro. It was made to commemorate the 10th-anniversary reprint of the Konjiki no Gash!! manga in a smaller format (bunkouban) with more chapters per volume than the regular tankoubon.