His Legion callsign was Pale Rider (ペイル・ライダー, Peiru Raidа̄?).
He was the personal knight and caretaker of Augusta Frederica Adel-Adler. After the Federacy's forces managed to breach the defensive line at his posting of Rosenfort and the apparent death of his liege, he was assimilated by a Tausendfüßler and became a Legion Shepherd.
As a pureblooded Onyx, Kiriya was an adolescent with jet-black eyes and hair in life. After becoming a Shepherd, his consciousness was hosted in the railgun type Morpho.
According to Frederica, Kiriya was a serious young man. In contrast to his distant cousin, Shinei Nouzen—who often ignores customs and regulations—Kiriya was rule-abiding and did not take well to rulebreakers. He was also stubborn and fiercely loyal to his princess, Frederica, and continued to fight for her despite the hopeless situation of the imperial royalists.
However, after losing his family and friends during the war, Kiriya began to descend into madness. With Frederica's apparent death, Kiriya went insane and did not stop himself from being assimilated. He was willing to become a Legion Shepherd and swore to destroy all enemies of his princess.
Born in RY 347 / SY 2127. Kiriya was a descendant of the Nouzen Clan, the famous Onyx family whose members served in Giadian Imperial army and Imperial guard for generations. At the age of eleven, he was assigned to be Augusta Frederica Adel-Adler's personal knight and caretaker.
During the civil war between the Imperial loyalists and the revolutionaries, Kiriya was the leader of Augusta Frederica's royal guard. As the revolutionaries hoped to shut down the Legion by capturing the empress, Kiriya and other Royal guards were often deployed to the battlefield. As the war progressed and the loyalists' situation continued to deteriorate, Kiriya began to lose his sanity. He became obsessive about protecting Frederica and increasingly enjoyed the slaughter of his enemies.
When the fortress was finally captured, Kiriya witnessed Frederica’s bloodstained mantle. Believing that his empress now had died, Kiriya was completely consumed by the madness , allowing himself to be assimilated by the Legion.
Kiriya was a highly-skilled warrior who specialized in melee combat like his distant relative, Shinei Nouzen. As a knight of the Nouzen Clan, Kiriya piloted a unique model of Feldreß instead of the staple Vánagandrs. His personal Feldreß had thick composite armor, a heavy 120 mm tank turret, and a powerful propulsion system to support its massive frame. Kiriya's fighting style was based on utilizing the heavyweight frame and high-output power packs of his Feldreß to trample opponents.
His skills remained intact even after becoming a Shepherd. During his battle against Shin, Kiriya completely saw through Shin's intention of moving into his blind spot and countered him with movements which were seemly impossible for the 1,400 ton Morpho.
“I will kill them all.” ― Kiriya Nouzen as the Legion Shepherd, Pale Rider
- As a shepherd, Kiriya is so unhinged that a fellow legion questioned his sanity and recommended to "recondition" him, since he ignored the request to capture Shinei alive and obliterated an entire squadron.
- Although Kiriya believed all of his immediate family were dead, they actually survived the civil war. Kiriya’s father, who loathed the leaders of the loyalist faction, had defected to the revolutionary army soon after the war began.