Haku Rei is a General of the state of Chu, He is around the same age as Shin, Ou Hon and Mou Ten and a part of Chu's young generation of military commanders alongside his best friendKou Yoku, Haku Rei also is the youngest member of the Ten Bows of China and is said to be currently ranked third among them.
Haku Rei appears to be a serious and irritable person and one who takes his job seriously. When Kou Yoku steps out of line, he often scolds him or warns him. When talking to Kou Yoku, he gets frequently irritated and this is shown by a cross popping vein in his speech bubble. He seems to be the calm and rational one out of him and Kou Yoku. He could be considered prideful since he calls himself the third-best of the Ten Bows of China, but this could be taken as him being realistic if his archery really is the third best.
Haku Rei’s sister Haku Sui asked him to use his bow to protect her husband, Rin Bu Kun. He spent many years touring the Southern battle lines with Rin Bu Kun and Kou Yoku.
Haku Rei is first seen on the Chu/Qin border with Rin Bu Kun and Kou Yoku. He comments on how much the Qin have gained from their alliance with Zhao and upon talking to his superior, realizes that they will soon be fighting the Qin. He is sent to stop Kou Yoku from engaging the Qin and shots Shin off his horse. Introducing himself, he states that it is good to see that Qin has tough commanders their age and leaves with Kou Yoku in tow.
During the Battle of Kankoku Pass against Qin, Haku Rei is placed in the Chu 1st Army along with Kou Yoku, led by General Rin Bu Kun. He gains the attention of Mou Ten, after sniping Commander Rin Bou from a great distance and then puts his attention on Riku Sen whom he believes to be the Captain of the Gaku Ka Unit. He is caught by Mou Ten's trap and would have been slain, if not for Kou Yoku's timely arrival. Then his unit pulls back to give support as Kou Yoku's forces battle with the Gyoku Hou Unit. When his platform cart arrives, he planned to snipe Ou Hon and Tou but unbeknownst to him Mou Ten and a few of these soldiers had been hiding under the cart. He attempted to shoot Mou Ten but missed before Mou Ten cuts his bow in two which gave Tou enough time to defeat Rin Bu Kun.
The next day he and Kouyoku are transferred to the 2nd Army said to be dangerous even for allies; under the command of General Ka Rin. Later that day, everyone from the first army above the rank of 1000-Man Commander was gathered up. They were shocked to meet the giant, cold-hearted General Karin. She calls out Rinbukun's lieutenant Ro Kin. As he pledges his loyalty, she kicks him breaking his neck, saying she has no use for "incompetent fools who reek of baldie." And that if it was up to her, they would all be executed. Also, she declares that the remnants of the 1st Army fight that day with no assistance from the 2nd Army. And if they are unable to slay Tou they will all be executed. She leaves telling them that if they tell anyone about her height their heads will roll.
They proceed to attack the Qin Army with no tactics.
Haku Rei and Kou Yoku make an appearance in Chapter 366, in which they are grouped with Shin, Ou Hon, and Mou Ten, while Ri Boku talks to Kaine and Fu Tei about the conditions of other states after the Coalition Invasion.
Karin sent Haku Rei and Kou Yoku to assists Juuko army in repelling the Qin invasion. They flanked Roku O Mi Army army as soon as they arrived. But disengaged the fight when the unexpected arrival of Wei army came to join the battle as Qin allies.
With the sudden turn of event, Juuko army strategist has reform the formation and have set Gen U and Haku Rei to face Wei army. Haku Rei army provided assistance to Gen U's army who was pushed back by three simultaneous charge of Wei Generals. As the battle continues, Gen U slain Ba Kai of the Wei general, turning the tables around and slowly tear down the Wei's weaken left flank.
The rest of the battle was on a standstill as neither give a foothold nor gaining the upper-hand, when the CHU HQ was under attack by Tou Army, Haku Rei took the opportunity to snipe at Tou who dodged it as he is fully aware of Haku Rei's abilities. But it has given enough time for Kou Yoku to reach Tou before being interrupted by Ran Bi Haku. Shotly after, the CHU HQ was taken down and captured, Gen U ordered Haku Rei and Kou Yoku to withdraw and regroup at Juuko city.
As one of the Ten Bows of China, Haku Rei can snipe enemies from great distances and his shots being powerful enough to pierce through armor or knock a person off there horse while blocking his arrows.
