He has a small beard, thin mustache and a warrior's build.
Ryuu Koku has an enthusiastic yet humble personality as he calls Mou Bu's attempt to recruit him a jest. Despite this humility, he demonstrates a different side towards those under his command such as Shin and Kyou Ki as he nags them constantly about their failures and issues.
It is assumed that he has served in Ou Ki's battles in the past and has worked his way past being a 1000-Man Commander. As the commander of the 2nd army, he is in charge of leading 12,000 troops into battle. He nows serve as a General under Great General Tou.
Ryuu Koku is first seen, prior to the battle, with Ou Ki and his other vassals returning from a training session.
During the Battle of Bayou he is placed in charge of the 2nd army of Qin. At the meeting, Mou Bu has with Ou Ki, he is placed under Mou Bu's command along with the other commanders so they can attack the Zhao headquarters at once. On the fourth day, his army charges at the Zhao headquarters some moments after Mou Bu's own, catching the Zhao by surprise. His army engaged Man Goku's forces before the Zhao retreated when Chou Sou moved their HQ. After the Zhao army retreats, he states that there are few places where they can deploy such a large army and they must be aware of how the Qin will react to this fact. Having no objections to Mou Bu's orders to pursue the Zhao, Ryuu Koku reminds him of his promise to Ou Ki involving his range and accompanies the Qin general's army.
He helps guide both his army and Mou Bu's to the relocated Zhao HQ and is commended for this by the Qin general. Asking if they would stick to their original plan, Mou Bu declines and orders them to attack immediately. As the two armies battle, Ryuu Koku notices that the Zhao are damaging the Qin forces more than expected and their armies are heading farther away from the visible range of the Qin HQ. Seeing Hou Ken present in the battle, he orders Qin troops to surround him and take his head. His army follows after that of Mou Bu's who was busy pursuing Hou Ken into a narrow path with steep cliffs. Seeing that it is a trap, Ryuu Koku warns Mou Bu and barely escapes the falling rocks thrown by the Zhao. After informing Moubu that they've lost about half their forces to the trap, he warns of future traps and advises them to retreat but his advice is disregarded. Fighting alongside Mou Bu's battered army, he is relieved to see his lord arrive with his army in tow. Seeing Ou Ki's employing a strategy to hastily eliminate the Zhao HQ, Ryuu Koku states that it is not like his lord to be in a rush and wonders why he is doing so now. He appears along with the remaining troops in Mou Bu's army to create an escape path for his dying lord amidst the fighting.
He later served as a witness when Tou was given command of Ou Ki's Army as per his lord's dying wish.
He has impressive navigational abilities as he was praised by Mou Bu when he led their army to the relocated Zhao headquarters in the mountainous region.
He is said to be the most quick-witted among the Tou Army's inner circle.