Kakusei Sol (which means "Awakened Sol" in Japanese), AKA Bousou Sol ("Rampaging Sol" in Japanese), is an awakened EX version of Sol Badguy that only appears in Guilty Gear Isuka. He is one of two bosses in its GG Boost Mode, the other being Kakusei Ky.
Kakusei/Bousou Sol uses a red awakening power coupled with a permanent Dragon Install-like effect (which however, must go through a refresh period that forces Sol into his pseudo-stunned state each time), fast-regenerating Tension and impressive fire techniques. Defeating Kakusei/Bousou Sol and Kakusei Ky on the last stage of GG Boost mode unlocks Zako 1, 2, and 3.
In order to unlock him, the player must first have Sol's EX version unlocked by beating Arcade Mode. Playing GG Boost or Scramble as Robo-Ky II in RKII Factory Mode on at least Normal difficulty, one must defeat Kakusei Sol and Kakusei Ky in Stage 5-E (Last Dance) with 1,400,000 points or more and not have used any warp points. One must then choose not to return to the factory and a giant Robo-Ky II ("Robo-Ky II Substance") will appear. Defeating it unlocks Kakusei/Bousou Sol and Ky.
To select him, the player must simply highlight Sol Badguy on the Character Select Screen and press Start twice. Kakusei/Bousou Sol can be unlocked also through beating the Robo-Ky II Substance first and unlocking EX Sol later.
Compared to normal Sol, he mostly mirrors most of EX Sol's moveset. But he comes with these specific differences:
- Gun Flame, Volcanic Viper version on the ground, and Bandit Revolver are now enhanced to their Dragon Install-versions by default.
- Gun Flame on the ground retains its normal version input of + . Gun Flame Feint also returns with the same input ( + ).
- In midair however, it still retains its + or input, only it now inflicts multiple hits. Depending on which part and angle it hits the target at, it can travel through the foe. If it the projectile lands on the ground, the launching row of flame bursts from the normal version Gun Flame will occur with the same hit effect.
- Volcanic Viper version on ground and both the airborne and versions go at a much lower height, and can no longer perform Tataki Otoshi off of it.
- Grand Viper itself has now two different versions; version involves Sol instantly rising into the DI-powered Volcanic Viper after the grounded dashing rush (where Tataki Otoshi can be performed off of it as aforementioned). The version however, has him leap into a DI-version Bandit Revolver.
- Riot Stamp now has Sol followup with a downward flaming spike kick upon landing the initial flying kick, which is the original held-down- button version of Bandit Revolver back in Guilty Gear X.
- Retains Tyrant Rave ver. β/Beta akin to normal Sol with the same input ( + ).
- Savage Fang is now enhanced to have the rising flames occur 4 times in succession.
- Via paralleling Kakusei Ky's unlisted ground Overdrive, Kakusei/Bousou Sol gains a new unlisted midair Overdrive via the same input as the aforementioned Beta Tyrant Rave ( + in midair) dubbed as Dragoon Revolver.
- The move is essentially a stronger version of his midair Gun Flame, where Sol performs a Bandit Bringer-esque punch that shoots a large fireball down at a diagonal angle, causing it to emit a row of 4 DI-empowered Gun Flame bursts upon it hitting the ground.