After leaving the Forest Zone, the three Spirits assisting Hikaru's group could no longer accompany them.
Relations between Spirits from different zones weren't exactly friendly.
Healing Zones like this, where you could seek recovery from the Aromages as long as you didn't cause trouble, were rare in the Critical Nexus.
So the Spirits could only wait outside the area for Hikaru and the others.
Not that it mattered much, once you reached the zone border, you could board a KaibaCorp train to other regions.
Hikaru didn't keep them waiting. He told them to head back to the Knight Zone. Meanwhile, he and the others boarded a KaibaCorp train.
"This area's undergoing renovations soon. You students can stay at the local base for a while," a KaibaCorp staff member informed them when they tried to head elsewhere. They were offered free dorms near the station, plus spare classrooms for study.
Duelists could even wait at the station to ambush incoming mark-holding Duelists and challenge them directly, saving travel time.
With the tournament lasting half a year, KaibaCorp had made all sorts of preparations.
The station even had a large Duel Field ready.
Since there was no rush, Hikaru discussed with his two companions and decided to stop at the Forest Station for a while, to review coursework and teach Celina alchemy.
Celina was completely clueless about alchemy.
After Professor Banner's passing, Duel Academy had stopped teaching it. But Hikaru felt it necessary for Celina to learn if she wanted to follow his path.
After all, in this world, "alchemy" was a manifestation of "Fusion."
Jaden, with his extreme alchemy talent, could use Fusion to create countless new HEROes. Hikaru could also use alchemy to custom-create the low-level monsters he needed.
Celina hadn't considered changing her Deck. She wasn't firmly set on the Fusion path, either. But being in a "not sure what to do" phase made it the perfect time for her to absorb new things.
Hikaru kept the lessons simple, if she liked it, he'd teach more; if not, he wouldn't force her.
Alchemy demanded talent.
Surprisingly, Celina seemed to have some.
Unlike Jaden's innate talent or Hikaru's integrative aptitude, Celina's gift wasn't "strong" but leaned toward reconciliation and coordination.
An incomplete soul.
Hikaru watched her and recalled what Tierra had told him earlier.
Celina fiddled with an experiment, tapping a metal rod until it glowed green. Her face lit up in joy, and she excitedly looked at Hikaru, holding the result with trembling hands.
Hikaru clapped and praised her sincerely.
Her "incomplete soul" wasn't like Rex Raptor's issue. She simply had less soul mass than other humans.
Though her "strength" far exceeded her peers, the "amount" was low.
Hikaru understood.
In the original story, Celina was one of "Zarc's" fragments in the Fusion Dimension.
As someone who could split souls and even worlds through cards, her talent was unquestionable.
She'd just need time to fill the gaps. Unlike Hikaru or Jaden, she couldn't progress as efficiently.
So teaching Celina alchemy was definitely the right call.
Having lost her direction, with only "Fusion Club seniors" and "Dueling" left, she finally showed curiosity toward something new.
"Why do these two things glow when mixed, Master?"
Having never seen such fun experiments growing up, always wandering or locked up studying Duels, Celina's eyes sparkled with childlike curiosity.
"Ha... Alchemy's pretty magical, huh?" Hikaru smiled and explained the principles, just like Professor Banner had taught him.
While teaching, Hikaru also reflected on his own studies.
After finishing the "Dimensional Gate" and its improvement, Hikaru wasn't about to put alchemy aside. He kept diving into the Emerald Book, never forgetting his goal of reaching the "Realm of the Spellcasters."
During this time, Hikaru had solved two more "puzzles" and reconnected with two of Professor Banner's old friends.
Not Aleister, but still good progress.
However;
Lately, Hikaru's research had hit another wall.
This time's project was arguably the hardest yet, even tougher than mastering Super Polymerization.
The basics of alchemy were destruction and recreation, purification and deepening.
Destruction and recreation, Hikaru had mastered that. Purification and deepening, he could do that in Duels, too.
But what he really wanted...
Meanwhile, Celina started tinkering with a distillation experiment again. Taking advantage of the break, Hikaru reached into his waist pouch and pulled out two cards.
[Armityle the Chaos Phantom] and [Raviel, Lord of Phantasms].
Unlike the now fully stabilized Armityle, Raviel's card was cracked and lifeless.
Maybe because of the Fusion Army's failure, Leo Akaba hadn't been able to nourish the Sacred Beasts' bodies. This replica card wasn't doing well either.
Of course, that didn't matter to Hikaru.
He hadn't forgotten: Armityle had been born from Uria, Hamon, and Celina's drawn "Hex-Sealed Fusion."
That card held special meaning!
Yes.
No mistake!
Hikaru's next goal was destruction, recreation, purification, deepening... to create an ultimate Fusion card.
Compared to his other experiments and projects, this alchemical task was entirely new territory.
Because for Hikaru, every Fusion Monster was already "gold."
He hadn't even successfully crafted a Fusion Monster Card yet!
Ha...
So this pursuit was practically making the Philosopher's Stone!
In the end, he'd become the "new-wave alchemist" that Fullmetalfoes Alkahest had mocked, chasing the Philosopher's Stone and ignoring the gold.
He shook his head and put the cards away.
This project was too difficult.
His current alchemy knowledge, application, and performance had all reached their peak. With his Emerald Book, he could even alter his appearance via special alchemical means.
There was almost no room for further growth.
In other words, just like when observing D-Wheels before, his only path now was breaking through from other angles.
Like teaching others... or seeing what other people's Fusions looked like.