: December 7th, 2035: 11: Red king : Prominence (Leader): 5th Year- 6th Year: Scarlet Rain: 9: Judgement Blow: Neuro Linker

Yuniko Kōzuki is the second and current Red King and also the leader of the Red Legion, Prominence.When Haruyuki first meets Yuniko, she has a personality of that of a normal girl. She was sweet and caring to Haru. She presented good manners such as greeting him and was shown to be able to cook well. Yuniko is an elementary student and attends a private school. Her duel avatar is Scarlet Rain who is the current Red King following Red Rider.

As the 2nd Red King after Red Rider, the first Red King, she is one of the few Level 9 players. She is nicknamed 'The Immobile Fortress' due to her fighting style where she boards her huge armament with powerful long-range artillery that allows her to defeat legions of enemies while standing in the same place.

She is also known to have knowledge of the Incarnate System due to her being one of the Six Kings of Pure Color. She later demonstrates her abilities with the Incarnate System when she helps teach Haru and Taku to use it.