Li Mu and Hai Yin is a side story oneshot, that follows Riboku and Kaine's past. The story covers how the two meet in Yan Men province and how they deal with the Xiong Nus tribes that regularly raid Yan Men.
- The author mentioned that he might include this short story as a background story for Riboku and Kaine in his Kingdom manga, but has doubt as it may be awkward to include an already published manga story in another manga. This story may therefore be canon in regards to the Kingdom manga.
- Link: http://mangafox.me/manga/li_mu/c000/