There is a fundamental difference between an Animagus transformation and a Saiyan's Great Ape transformation under a full moon.
A Saiyan's transformation is a purely biological expansion into a giant simian form. Unless they are wearing specialized, high-stretch combat suits, their regular clothes are instantly shredded, and any items they are carrying naturally fall to the ground.
When Little Goku transformed last time, it took him quite a while to recover his Four-Star Ball and Power Pole.
The Animagus transformation, however, bypasses this inconvenience. Because the essence of an Animagus is a specialized application of Transfiguration, everything on the wizard's person—clothes, accessories, and gear—is integrated into the animal form as fur, scales, or claws.
There is no risk of losing equipment, as everything reverts perfectly when the user returns to human form.
"Is... is this the 'Great Ape' Goku spoke of?"
Dumbledore watched the transformed Little Goku, his body trembling slightly despite himself.
"It truly is terrifying!"
The sheer, world-shaking pressure emanating from the Great Ape was enough to make even a wizard of Dumbledore's caliber feel a chill of dread.
It was a disparity in the very hierarchy of life. With a deafening roar toward the sky, the Great Ape's cry actually dispersed the storm clouds and lightning, turning the sky clear in an instant.
"Goku, how do you feel?"
Dumbledore dared not be careless. He levitated into the air, using a Sonorous Charm to project his voice.
Although he had confidence in his modified Animagus ritual, feeling Goku's current power left him riddled with anxiety. If the ritual failed and Goku lost his sanity in this form, his current destructive potential could bring about the end of the world.
Even knowing that cutting the tail might force a reversion, it was a gamble he didn't want to take.
Fortunately, Goku's voice rumbled steadily from the Great Ape's massive maw:
"Grandpa Dumbledore, I'm okay! I just feel... more... more... like I want to fight than usual! But I can keep it under control."
Using the Animagus method to trigger the transformation had indeed allowed him to retain his reason, yet the primal ferocity and destructive urges embedded in the Saiyan bloodline still exerted an influence.
In this state, he was hungrier for battle, more inclined toward destruction, quicker to anger, and significantly colder.
Under normal circumstances, Goku tended to hold back, rarely dealing lethal blows unless by accident.
In his Great Ape form, however, his restraint thinned; any enemy faced would likely be torn to shreds before he could check his strength. He realized then that unless it was a matter of life and death, it was better not to use this form—and it was definitely off-limits for events like the World Martial Arts Tournament.
After taking a moment to sense his titanic physical strength and his Ki, which had swelled tenfold, Little Goku acclimated to the power and reverted to his normal state.
"Grandpa Dumbledore, let's get back to the Guild!"
Tomorrow was the scheduled day for the joint operation to suppress Grimoire Heart. He had finished his Animagus training a day early—excellent luck.
"Very well, let us depart."
Dumbledore nodded and shrunk himself down to enter Goku's storage capsule once more. He had already settled affairs at Hogwarts, bringing a mountain of magic books with him. He intended to stay in this world for a while to engage in deep magical exchange.
With a blur of motion, Goku arrived at the clearing in the East Forest and released Dumbledore.
Together, they walked into the Guild Hall. However, the usually boisterous hall was nearly empty, save for a few members whose faces were etched with worry.
"Little Goku! Mr. Dumbledore! You're back early!"
Behind the bar, Mirajane's face lit up with surprise and relief at their appearance.
"Mirajane-san, what's wrong? Where is everyone?" Goku asked, puzzled. Dumbledore, however, had already deduced the reason.
"Has the suppression plan gone awry?"
"Ultear sent word—the plan was exposed," Mirajane explained quickly, recounting the morning's events.
"She had no choice but to lure Grimoire Heart to Tenrou Island ahead of schedule. The Master and the others received the message and immediately mobilized to support her."
Even though Makarov had prepared extensively, Mirajane felt a lingering dread. A shadow hung over her heart; her intuition screamed that the Master and the others were walking into a disaster. Seeing Goku and his teacher return early was the first bit of good news she'd had all day.
"I suspect it is a trap," Dumbledore said, his brow furrowing.
If the plan were truly exposed, the odds of Ultear escaping were slim, and the odds of her "luring" the entirety of Grimoire Heart to Tenrou Island were even slimmer—unless the Guild Master, Hades, was a complete fool.
But even if it were a trap, Dumbledore knew Makarov's character. He would walk straight into it. If it was a trap, it meant Ultear had likely been captured, and they had to save her.
Furthermore, this was a rare opportunity to gather all the "Masters" of Grimoire Heart in one place. In the end, victory would be decided by raw strength.
Dumbledore wasn't overly worried for their safety, though. He knew that the current Goku possessed enough power to sweep through the strongest fighters of this world—or even destroy the world itself.
"The fight started early? We have to hurry, or it'll be over before we get there!"
Goku didn't share Dumbledore's strategic concerns. He was only worried that if he arrived too late, the Master would have already finished the job, leaving him with no one to fight.
He was itching to test himself against Master Hades, whom Makarov had described as having Heavenly King-level strength.
"I know the location of Tenrou Island. I'm coming with you," Mirajane said, waving her hand to manifest a magical map in the air.
"We head to Galuna Island first, then fly south directly to Tenrou."
Goku glanced at the map, tucked Dumbledore and Mirajane into his capsule, and used Apparition to instantly reach Galuna Island. Once there, he summoned the Flying Nimbus, released Mirajane to act as his navigator, and streaked toward Tenrou Island at maximum speed.
Meanwhile, in the skies above Tenrou Island, inside the Grimoire Heart magical airship...
Hades looked down at the magically bound Ultear and smiled thinly.
"I didn't expect you to betray me. No matter—this simply allows me to eliminate the nuisance of Fairy Tail ahead of schedule."
"Master Hades, I trust you haven't forgotten your promise."
A man leaning on a staff walked forward. His hair was stark white, and his face was etched with strange, magical tattoos.
"Master Brain, once this is concluded, I will hand Jellal over to you in his entirety," Hades replied with a chuckle.
The newcomer was the leader of the Oración Seis. It was thanks to his subordinate, Erik (Cobra), and his Sound Magic—which allowed him to hear the very thoughts of others—that they had intercepted the truth from Ultear's heart and learned of Makarov's entire plan.
"And the Organic Link Magic I require."
A young, elegant man with long black hair carrying a bizarre grimoire approached. Hades' eyes narrowed slightly.
"Rest assured, Underworld King. Once our goal is achieved, the data regarding Organic Link Magic will be yours."
Hades knew Brain's background and his designs for Jellal, but this "King" from Tartaros remained an enigma. He couldn't quite fathom the man's obsession with Organic Link Magic.
It didn't matter for now. The priority was the alliance between Grimoire Heart, Oración Seis, and Tartaros. Together, they would bury Fairy Tail here and crush anyone standing in the way of his ultimate goal.
Once he found the Black Wizard, Zeref, and ushered in the "Ultimate Magic World," even this Underworld King would have to bow before him. Turning to a nearby lacrima crystal, a satisfied smile spread across Hades' face.