Gradually, the Black-and-Red Inazuma originally coiling around Luffy's right arm grew sparser, but in its place, mysterious lightning-shaped patterns slowly emerged on the surface of his arm.
These patterns shimmered faintly, as though they contained endless power and mysteries.
Without a doubt, this meant that the Color of Arms and Color of Observation Haki had truly begun to fuse, rather than merely coating the surface with Armament Haki and wrapping a layer of Conqueror's Haki around it as before.
That method could only be called layering, not true fusion.
At that moment, the atmosphere between the two grew increasingly tense and oppressive, as though a heavy presence had enveloped the entire space.
At this critical instant, as though their minds were in sync, both chose to strike at exactly the same time...
"Gen Style: One Sword Style: Draw-and-Cut!"
With a furious roar, the blade in Genryūsai Shigekuni Yamamoto's hand blazed with dazzling azure light. Like a brilliant meteor streaking across the sky, it slashed forward with unparalleled force.
At the same time, Luffy refused to be outdone and unleashed his own ultimate technique: "Gomu Gomu: Dragon: Extreme Beast Cannon!"
His arm instantly grew as thick as a mighty dragon, its muscles taut and its power surging.
That enormous fist smashed forward like a small hill, crashing into Genryūsai Shigekuni Yamamoto's fierce slash.
In an instant, heaven and earth seemed to change color.
First, an intense, dizzying light too brilliant to look at erupted, like the sun falling to earth, stabbing painfully at the eyes.
Then came a deafening boom that resounded through the clouds, as though the entire world had been shaken by its roar.
A violent hurricane powerful enough to overturn a train swept outward from the point where the two clashed.
Even the surrounding air seemed to tear