Allen Kōzuki

Allen Kozuki  (アレン, Kōzuki Aren) is a character in the Yu-Gi-Oh! ARC-V anime. He is a friend of Sayaka Sasayama and is a surviving resident of the Xyz Dimension.

Past
Prior Academia's invasion, Allen and Sayaka were student from Heartland Duel School's Clover branch, the same branch where Kaito studied under Yūshō's tutelage who was the teacher of their branch. When Academia attacked, Allen and the others from Clover and Spade branches tried their best to survive, but they eventually overpowered and were forced to be in hiding. Allen revealed that while Academia was invading, Yūshō suddenly vanished, leading him to think that he had abandoned them.

Yūya vs. Kaito
Allen and Sayaka reunited with Shun, who got transported back to Heartland with Yūya, Shingo, and Gongenzaka. The three of them then looked for Yūya and the others and met the refugees that Yūya and the others had saved before who told them their location, arriving in time to stop the Duel between Yūya and Kaito before it was too late. Along with Shun and Sayaka, Allen assured Kaito that Yūya and the others are allies, expressing his gratitude that bringing three new allies was extremely helpful for them. Despite these assurance, Kaito still refused to fight together with them and left the scene.

Resistance Hideout
At their hideout, Allen introduced himself and Sayaka as he told Sayaka, who was distributing food even though it's not her shift, not to overwork herself. He then commented on Yūya's resemblance with Yūto, thinking that he was in fact Yūto himself after he saw him using "Dark Rebellion Xyz Dragon", but Shun cleared this confusion. Allen then revealed that while Yūto and Shun were gone, the Academia had launched a massive offensive attack, nearly wiping out Resistance's Spade and Clover branches, forcing them to be in hiding. Their conversation was cut short when Sayaka questioned Yūya's connection with Yūshō, and the latter revealed that Yūshō is his father. Hearing this, Allen explained that Yūshō was their teacher and had abandoned them during the invasion, shocking Yūya.