Super Saiyan Blue Kaio-ken (超サイヤ人ブルー界王拳Sūpā Saiya-jin Burū Kaiōken, lit. “Super Saiyan Blue: Fist of the King of the Worlds”), also known as Super Saiyan God Super Saiyan: Kaio-ken, or Blue Kaio-ken in the manga, is a technique which in the anime, consists of using the Kaio-ken, or in the manga, applying the principles of Kaio-ken while transformed as a Super Saiyan Blue.
In the anime, this variation of the Kaio-ken synchronizes the two separate power boosts between Goku’s godly transformation and the special technique, which is emphasized by the double aura effect, placing a crimson Kaio-ken aura outside of a typical blue Super Saiyan Blue aura. The outer Kaio-ken aura manifests as violently fluctuating and jagged while the Super Saiyan Blue aura maintains a gentle, flame-like contour. When using this transformation for the first time, the energy aura is so intense that Goku’s blue hair appears several shades lighter than normal, and his skin appears to be illuminated by the Kaio-ken’s aura to a dark shade of pink. Additionally, Goku’s clothes are affected as well; his bright orange Gi becomes dark red, whereas his dark blue belt, wristbands and shoes turn purple. The light generated by this technique is so intense, that the whole surrounding area is illuminated to many shades of red.
In the manga, this state retains the same appearance as both it’s predecessors Super Saiyan Blue and Perfected Super Saiyan Blue, only that it’s aura lacks the crimson aura from the Kaio-ken technique and it’s blue godly aura taking on a much pressured and fiercer look due to the sheer intensity of Goku’s attempt to shatter his limits.