Gaku Ei wears a plumed helmet with two long horns sticking out to the side. His armor is also different from a traditional general's armor due to the fact that he has 2 long shoulder guards on both sides. Additionally, there is also an ornate X going through the middle of his armor. He also has a long beard.
Before joining the Kei Sha army, he was a lone-wolf warrior with a serious personality, who simply killed his opponents without feelings or remorse. When Kei Sha complimented for his hard work, It was the first time to Gaku Ei, that someone said something good about him even with just two words, "Good Work". After that, he became more attached to Kei Sha. In his first appearance in Battle of Koku You, he was loyal to Kei Sha and has the tendency to make sarcasm such as height difference between Kin Mou and himself or mock his enemies whenever they fall to Kei'Sha trap.
When he found out the truth, the death of Kei Sha, he became a vengeful man, even going so far to harm anyone who gets in his way to avenge his master's death. He blamed Kin Mou and Ki Sui for not telling him about Kei Sha 's fate earlier with fierce temperament. Even going as far as to attempt to kill Ki Sui and Ba Tei after hearing that Ki Sui insisted on abandoning the hill to Qin forces, led by Kanki. On one occasion, in a fit of fury, he harmed and killed a soldier who was mourning Kei Sha's death when he couldn't answer his question clearly.
Before joining Keisha's army, Gaku'ei was a lone wolf with no ties. After becoming Kei Sha's deputy, he became his extremely loyal follower and served Kei Sha for many years. He was shown fighting under Kei Sha against Yan during unknown battle.
Gaku Ei made his first appearance riding alongside Kei Sha, Kin Mou, and Ki Sui. He questioned Ki Sui's of letting his two 'brothers' performing such dangerous operation on the first day of battle on Koku You. But was grateful upon hearing the operation was a success and made sarcasm on Kin Mou's short height.
He was seen commanding the right wing along with his Unit, facing against both Zen Ou Clan and Rai Do Clan. Stalling time to allow the rest of Zhao's right-wing to trapped and finish them off in a fatal blow. But Raido realized the trap before it could happen and devised a plan with Zen Ou, allowing them to escape from Kei'Sha 'trap'. On the second day, Gaku Ei and the ring Wing made a standoff point against Raido's army. Nothing much has happened. After Hi Shin Unit made huge progress of crossing the river against the Rigan's left-wing commanded by Ba Tei on Ryuu Tou's guidance. The day everyone waits for Kanki's first major move, Kei'Sha and the rest of Zhao's commanders were left dumbstruck as Kanki didn't make any moves for the whole day. Leaving them clueless as to what was 'Kanki thinking'.
The next day, he was mentioned that he and his right-wing were engaged with Raido's left-wing army. Unbeknownst to Gaku Ei, Kei'Sha was slain by Shin. Upon hearing the news of the death of Kei Sha, he made a vow to kill every last Hi Shin Unit and exact vengeance on Shin.
On the final day on the battle of Koku You, upon receiving news of the incident that Kanki has brought to civilians of Koku You and a letter of his intentions to bring 'greater tragedy' on Rigan. Gaku Ei and Kin Mou form a meeting with Kisui and Batei, an argument occurs between Kei Sha's commander and Kisui about the fate of Koku You hills. Kisui insisted on abandoning the Koku You hill entirely as his homeland was threatened by the Kan Ki army. Upon hearing this, Gaku Ei was enraged, even threaten to kill both Kisui and Batei as viewed as "desertion". He was stopped by Kin Mou who retaliates that should Gaku Ei continued the way he is, he'll have to remove himself and restart as a soldier. Stating that the fate of Koku You are decided by the highest rank and that Ki Sui takes command of the high ranking after Kei Sha's death. Kisui finally made his decision to abandoned Koku You hills to bring his army to chased Kanki's army (heading for Rigan).
Kei Sha army was left behind to defend the hills. They were forced to withdraw after losing strategic grounds to the combined strength of Kanki's half army, Hi Shin Unit, and Zen Ou Clan. Gaku Ei was last seen defending the lines, insists taking 'rearguard' against the invading Qin forces, to allow Kei Sha army on a full withdrawal, Kin Mou, knowing his intentions, persuaded him to withdraw and that taking on a suicide mission would mean to die in vain and telling him that vengeance will come when chances arise.
Gaku Ei was seen taking his unit of 10,000 armies alongside Bananji and Chou Garyuu army, to take a position as left-wing at Shukai Plain. He and his men took the first wave to charged against Akou's army. In the long run, Gaku Ei's men were losing in every ground from Akou's ruthless offense. But was saved by Banaji's tactics and gained a second wave, allowing them to gain equal footing against Akou's army. On the second day, he led his men to confront Ou Hon and Gyoku Hou unit, cooperating with Chou Garyuu, they entrapped Ou Hon and his unit in order to wipe them off completely but was unable to do so as Gyoku Hou unit made a full retreat and Ou Hon's went on to flank Bananji's army, causing damage beyond repair.
After receiving reinforcements from Zhao's HQ center, led by Gyou Un. On the day Gyou Un made his first move to charge right through Akou's frontlines. He was stunned by how powerful the Gyou'Un army was as they easily broke through Akou's army front line. He led his men to face against Akou's army, not wanting to let the living legend to take all the glory.
The fight would continue on in 'attrition warfare' till on the 9th day at Battle at Shukai Plains where Qin's right Wing devised a plan to take out one of the four commanders of Zhao's left-wing. Gaku Ei, believing to be the easiest target. Gaku Ei and his army would find themselves facing against Hi Shin Unit and Gyoku Hou unit together. When Gaku Ei and his army engaged Hi Shin Unit with the intention to wipe them out for slaying Kei Sha back in Koku You hill. He and his men overwhelmed Hi Shin Unit in every corner, to the extent that even the Gyoku Hou unit faced difficulty in punching through Gaku Ei's army. While in the midst of the battlefield, Gaku Ei was seeking for Shin. When they finally met face-to-face, Gaku Ei charged at the idled Shin to take his life. Only to have his final moment witnessing Shin slashed him in half by a single blow, resembling how Ou Ki swings his glaive against his foes.
Among the generals on the Zhao Left Wing in the Battle at Shukai Plains, he is stated to be the weakest of all of them. However, Ka Ryo Ten has stated that he can be considered one of the strongest hitters in any other army. During the Battle of Koku You Hill, he was able to clash equally with Kan Ki's lieutenant Rai Do. His style seem to rely on fearless direct charges during which he was shown to mantain high morale of his soldiers.