Zatch Bell!! 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.