She is the first healer of the Accelerated World. At the same time, she is also one of the Originators.
In an attempt to get the Seven Roses, a special gun created by Red Rider, White Cosmos manipulated Black Lotus, to kill him. She fabricated a reason that Red Rider plans to force the maintenance of the Peace Treaty by giving each a gun. This gun would decimate any attacking legion.
After Nega Nebulus disbanded, Kuroyukihime found the Seven Roses in her inventory. She tried to fire it however it would not. She realized this gun was meant as a symbol of peace and friendship. Red Rider created it with the belief that their friendship would continue. Kuroyukihime confronted her sister. She demanded White Cosmos to duel her. However, White Cosmos replied that Kuroyukihime could never beat her. Realizing this, Kuroyukihime took out a boxcutter and wounded White Cosmos. It was a small wound, however White Cosmos made it larger. This resulted in Kuroyukihime being exiled from her family.
White Cosmos also participated in the torture of Saffron Blossom, alongside Black Vise and Argon Array. She also witnessed the birth of Chrome Disaster. Her reasons for joining is currently unknown. In Volume 14, it is confirmed that she is, in fact, the president of the Acceleration Research Society.
She is the one of the few Burst Linkers that have the power to heal. She can also mask her presence in light. Specifically, she distorts light around her as camouflage.