Super Solar

Super Solar (スーパー太陽) refers to a unique and powerful transformation assumed by Issei Hyoudou, which increases his base strength by a great magnitude. As Issei continued to grow in power, advancements of the transformation began to surface.

Overview
Due to being a God born from the energies of the Sun, Issei is able to harness immense amounts of solar energy in order to enhance his physical attributes. This in turn gives him a massive increase in strength, energy, power, speed, stamina and durability.

Super Solar Transformation Line
Super Solar: The first evolution of Issei's solar transformations. This form was achieved by Issei during his battle against Riser Phenex in a bout of rage. While in this state, Issei's hair spikes up in a orange-yellow color, and he loses the pupils and irises in his eyes. His body is surrounded by a golden aura.

Hell-Fire/Solar Phoenix Form: The result of Issei absorbing Riser's flames while he was in his Super Solar form. In this state, his hair reverts to its normal style, though it is black in color. His left eye returns to the color of brown, while his right eye acquires a black-grayish color. On occasion, phoenix wings of pure hell-fire would sprout out from his back. Because he attained this form by absorbing Riser's flames while he was in the Underworld, Issei can only access the transformation whenever he is in the location, and therefore, cannot transform into it on Earth or Heaven.

Super Solar God: Issei's initial ultimate form which was gained by him absorbing the Sun entirely into his body. His hair lifts up slightly and is now a reddish-purple color. His eyes are sharpened, with his irises gaining a red shade. He is also much taller and thinner compared to his previous transformations. He is surrounded by a explosive and flame-like aura.

God Beyond Solar: The form assumed by Issei after his body was physiologically altered to that of a star. While in this form, his physical appearance remains mostly unchanged, while his body is imbued by a golden glow, and a double blazing aura of blue and white. This form is alternatively known as "The God that surpasses the Sun".

Morning Star: The form achieved by Issei after he absorbed the energies of the red supergiant star UY Scuti. In this form, Issei's hair spikes up and adopts a light pink hue in color, with the hair possessing pure-white highlights. His facial features are sharper, and his eyes are more menacing, showing noticeable intensity and sternness. His brown eyes change to a dark green-gray color, while his aura appears to be crimson-red on the inner layer, and the outer layer a darker shade of fire-like orange. The aura is also accompanied by bio-electric sparks, and his body is surrounded by an ominous black glow. It is implied that the hair color is in this form is originally supposed to be white, as Cao Cao noted that Issei's aura when absorbing UY Scuti was pure-white, and that in turn mixed with the red color of the supergiant star, causing it to turn pink.