Li Mu and Hai Yin is the third of four-side story one-shots written by Yasuhisa Hara before he began the official story for Kingdom. It was collected alongside "Meng Wu and Chu Zi" in the second volume of the Kingdom Omnibus books.
The story follows Ri Boku and Kaine's past and covers how the two met in Ganmon/Yan Men province of Zhao while dealing with the Northern Horsemen Tribes that regularly raided the area.
Summary[]
Ganmon, (Chinese: Yan Men) province was Zhao's equivalent of a lawless area on its empty northern frontier, with the Xiongnu raids inflicting crippling damages upon Zhao's citizens. And generals sent by Kantan end up dying before the year ends due to the vast armies the Xiongnu can muster. They decided upon Ri Boku (Chinese: Li Mu) to go to the battered province. After arriving through the stronghold, he puts his tactics in motion.
Knowing he can't take on the Xiongnu with the small garrison that's available, he focused on defensive tactics. Ri Boku himself begins drilling the villagers to fall back into Ganmon castle's walls whenever the raiders appear rather than waste outnumbered soldiers' lives on futile stands against the invaders. These tactics make a hot-blooded girl, Kaine (Chinese: Hai Yin) furious. She confronts Ri Boku during one such raid, despite his orders that nobody must move out but the general throws her into jail after knocking her unconscious. Despite past orders to execute all who disobey, Ri Boku spares her as he knows she's merely seeking revenge for her parents who died at the Xiongnu's hands. The raid was a failure, and Xiongnu only burns the empty houses. Eventually, they stop raiding regularly.
Sometime later, during a banquet celebrating Ganmon's harvest with no loss to the Xiongnu, Kaine leaves while calling Ri Boku a coward. When Ri Boku confronts her and explains how he can only use defensive tactics due to the lack of troops and commanders preventing him from permanently crippling the Xiongnu, Kaine asks if such tactics would disgrace Zhao and their people. The Zhao general then tells her a story about someone who was like her, a hot-blooded young man who wanted revenge for his parents' deaths in a war. With his 1000-man battalion and himself driven berserk, they charged the enemy recklessly. Despite heavy wounds, he succeeded in killing the enemy commander but lost everyone in his battalion, including his remaining relatives and friends. With Kaine realizing this was Ri Boku himself, Ri Boku explains how other people's lives are extremely valuable and that she should learn to treasure them unlike his foolish past self.
But Shou (Chinese: Zhao), one of Kaine's friends who was distraught over her frustration, reported what the Great General's tactics to Kantan, which leads to Ri Boku to be recalled and replaced by another impatient General. The battle started by the General ends in complete disaster, with casualties being incredibly heavy, including Shou, and the castle overrun. With the Ganmon garrison reduced to a handful of survivors, Kaine despairs over how her actions caused all her comrades to die, including Shou. While mourning her comrades at their gravesite, Ri Boku returns and promises a relieved Kaine that he won't leave again as she begins to cry. The epilogue notes that he helped the province stand up again.

Trivia[]
- This one-shot preceded Meng Wu and Chu Zi and Chapter 1 in terms of release. It came after two other one shots that were collected in the first volume of the Kingdom Omnibus - "Kongo (金刚)" being a pilot one-shot based Shin, Sei, and Ten while the other called Horse and Liquor for 300 Soldiers being a one-shot on Qin King Boku Kou and the Horse & Liqueur Mountain warriors.
- It was first published as a standalone one shot in April of 2004 with the release of Vol.18 of the 2004 edition of Weekly Young Jump magazine. It was later published within Volume 2 of the Kingdom Omnibus in June 2012.
- Hara has stated that it was this one shot's popularity that enabled him to serialize Kingdom as a manga series. He also mentions that he might include this short story as a background story for Ri Boku and Kaine in the series but had doubts as it may be awkward to include an already published one-shot manga story in another manga. This story, however, is directly mentioned by Yo Tan Wa in a conversation with Sei in Chapter 155, and therefore, is canon in regards to the series.
- The one shot and the comments on Ri Boku's campaign against the Xiongnu are indirectly mentioned by Yo Tan Wa in Chapter 155 in the manga.