Duel is an one on one fights that take place during battles. The opponents are usually higher ranked military officers such as Generals. When a duel occurs, the rest of the armies' soldiers tend to not interfere, as such fights are beyond the common soldier's caliber. As expected, the outcome of a duel could very well affect the outcome of the battle itself.
*Hou Ken and Ou Ki had a brief clash 9 years before the start of the story,after the former killed the latter's fiance Kyou.An enraged Ou Ki grievously wounded Hou Ken,but he managed to survive.Gi Ka shot Ou Ki in the second confrontation.
*The two fought multiple times in the past with Renpa having the upper hand all of the times and Mougou fleeing in fear. Their last duel was not decided, since it was interrupted, although Renpa still had the upper hand he managed to cut off Mougou's arm.
Shin had gained the upper hand and knocked him unconscious, but was then distracted by the attempted kidnapping of Ten. Fu Tei later regained consciousness, but was knocked off the city walls by Ryuu Sen before the duel was settled.
Shin wounded Houken with a thrust to his chest, followed up by a slash of his jump attack. Houken severely wounded was ready to fight back but was interrupted by general Shinseijou who told him to fall back and was escorted out of the battlefield. It should be noted that one of Houken's arms was incapacitated due to his duel with Duke Hyou earlier