After finishing talking with Tenjo Hikari about the basics, Kurosaki Shun was already prepared.
It would definitely be difficult for him to try and contact other people himself, but luckily, there was still his good bro "Yuto" in his team.
When she found out that Yuto had also come to this world, Ruri was very happy, but soon after she started worrying about Yuto's condition.
Yuto's situation was more or less the same as Shun's; he also left the Xyz Dimension to search for Ruri. However, unlike Shun, he didn't have extra work he needed to handle. And another thing was, Yuto himself was very worried about Shun, because when Kurosaki Shun lost his temper, he'd become extremely stubborn, and if no one was there to help, there was no telling what kind of trouble he might cause.
On this point, Tenjo Hikari more or less agreed.
In the original work, Kurosaki Shun could even, in the Pendulum Dimension, turn random passerby Duelists into Cards without a word, basically a bona fide revenge maniac.
Shun also decided to explain what was going on here to Yuto later, and he'd probably bring Yuto to see Ruri tomorrow.
Being able to meet her brother and her friend in a foreign land was a huge comfort for Ruri, and maybe because of that, she couldn't help but tell her brother about the thoughts she'd had before.
She wanted to study Spirit Studies at a school in the Fusion Dimension.
"How could that be okay, Ruri!"
"Eh, really! Ruri!"
Shun and Serena showed completely opposite reactions.
To Kurosaki Shun, having finally found Ruri, of course the plan was to keep her by his side every day like she was some national treasure to be protected, in case she got suddenly attacked again someday.
To Serena, Ruri going back to her own Dimension was only natural, so she herself hadn't held any particular expectations. Even though losing a same-age sister would probably make her already dull school life even duller, she still had her master and other seniors; there were always things to do every day, so she wasn't alone. But if same-age Ruri could stay around all the time, for her that'd obviously be the best thing ever.
Ruri was very displeased with Shun's reaction, but she was still a relatively rational girl, so she told Shun some of her own thoughts.
First, the two Dimensions had ended up with a rift because of the Fusion Army, and if they could have deeper exchange and study between the two Dimensions, that would definitely help break the ice further.
Second, the Spirit Studies taught in the Fusion Dimension was something she had never seen or learned back in the Xyz Dimension. She was very interested in it, and she'd already learned a lot of brand-new things recently; if she left now, it would be far too much of a waste.
She really wanted to learn all the remaining courses. That way, not only could she satisfy her own curiosity, she could also give back to the Xyz Dimension, bringing home enough useful, brand-new knowledge for the Xyz Dimension.
But to Shun, this was just too awful, too painful.
She actually wanted to study that terrible Fusion Dimension stuff—
Seeing that Shun still looked so unwilling, Ruri couldn't help puffing her cheeks and putting her hands on her hips as she stared him down, showing absolutely no sign of backing off.
"Ruri, about this, we really do need to think long-term."
"Eh? Even Brother Hikari—" Ruri was very surprised.
Shun was even more surprised.
He hadn't thought Tenjo Hikari would back him up on this.
Yet he then found Tenjo Hikari's next words were brutally realistic.
"Ruri, first, there's something you need to confirm, and that is: the qualification certificate we provide after graduation from Duel Academy—can that be used in your world? Does it mean anything?"
?
"Second, even if your Dimension's government can smooth over the related issues, you should at least go home and see your parents first, right?"
"At the very least, let your family know what actually happened and put their minds at ease. That's better, isn't it?"
"And another thing is, if you want to study related professional knowledge at our Duel Academy, it's actually better to go through the official, proper channels. That way you can focus on studying that content specifically, instead of having to split your attention with other courses."
...
Ruri hesitated for a moment, raising one hand to her chest, thinking for a while, then lightly nodding.
What Tenjo Hikari said made a lot of sense.
Tenjo Hikari hadn't considered any career paths or other things, nor had he thought about matters of Duels; instead, he took the standpoint of "if you really are doing cross-Dimension study abroad, what should you do," and because of that, this kind of persuasion was very meaningful. By comparison, Kurosaki Shun's outright refusal that allowed no argument was, in Ruri's eyes, nothing but "a stupid big brother's stupid decision."
Seeing there was still room to maneuver, Kurosaki Shun let out a breath of relief. Tenjo Hikari glanced at the time—there wasn't much left, and he couldn't keep the Fusion Dimension friends waiting, so he spoke up to say goodbye to Ruri and the others. Seeing this, although Kurosaki Shun still wanted to talk with his little sister for a while longer, he sighed and said goodbye to his little sister and "little sisters," and agreed on a time for tomorrow, when he'd bring Yuto to visit.
After settling these matters, Tenjo Hikari then headed to the Fusion Dimension base, where everyone from the Fusion Dimension had already been waiting a long time for him.
The Fusion Dimension residence had been simply decorated, with some colored lights and small fireworks. The moment Tenjo Hikari stepped through the door, they all lit up and went off together, and Tenjo Hikari froze for a second before looking toward his familiar friends.