Due to the uncertainty surrounding the time spent exploring other worlds (specifically, the imprecision in returning to the proper point on the timeline), Aoko waited until her university was on break before taking action.
She had asked her family members if they wanted to join her in exploring another world, and the answers were varied. In the end, only Touko was willing—or rather, only she was capable of accompanying Aoko.
First, as the Witch of Yumina, Alice couldn't leave the bounded field of the mansion for too long. Second, Arcueid, being a candidate for the planetary brain (not to be confused with Gaia as the Counter Force), couldn't leave the Earth-Moon system.
As for Artoria, she could technically join, but she was unwilling to leave behind the still-somewhat-withdrawn Gray. As such, the only participants in this interdimensional exploration were the Aozaki sisters.
Having already experienced one attempt in the past (albeit one that was, in a way, a failure), the rest of the household treated the sisters' outing as nothing more than a short business trip. They expected that the two might not even be gone for long—perhaps they'd leave and then return almost immediately. Thus, no one saw them off.
"Are you ready?" Aoko asked Touko while holding her hands to form a magic circuit.
Touko didn't speak, only nodding slightly to indicate she was fully prepared. Her equipment was similar to Aoko's, except the Cheshire Cat, a fat feline tucked inside Touko's backpack, occasionally shifting and moving.
Taking a deep breath, Aoko began chanting the spell for dimensional transfer. The incantation was slightly different from the last time, as the coordinates had been adjusted based on the world coordinates of Lina's dimension. In comparison to the coordinates of the Sea of Stars, these were far more complex when anchored to this world.
To account for the possibility of a failed transfer, such as ending up in the vacuum of space, Aoko cast interdimensional protective spells on both herself and Touko, simulating their current survival environment.
As for Touko, being a Third Magic user who had achieved soul materialization, she could theoretically roam space naked without any issues. The possibility of her Third Magic failing due to differing interdimensional rules wasn't a concern either. Touko's Third Magic, soul materialization, meant that even if her magic somehow ceased to function, she was already in a state of complete soul materialization.
Although Touko still looked human, she was a fully materialized soul possessing infinite energy. Aoko wasn't taking unnecessary risks; she had asked Touko if she needed additional protection, but Touko had confidently declined.
As the spellcasting for the dimensional transfer concluded, the figures of Aoko and Touko disappeared from the Nasuverse amidst a swirling, viscous distortion of space that resembled transparent, rotating liquid.
...
...
...
"Hey, hey, wake up." Aoko, snapping out of a momentary daze, heard Touko's voice and felt her sister patting her shoulder.
"Alright, alright, I'm fine," Aoko replied, glancing at Touko. "The transfer went way too smoothly this time. I guess my warning to Gaia last time worked…"
"You warned Gaia?" Touko gave Aoko a sharp look. "What did you say?"
"I told it that if it dared to mess with me during a dimensional jump again, I'd blow it up!" Aoko declared smugly. "I can pull it off!"
"Sigh," Touko sighed deeply, realizing that this was exactly the kind of thing her sister would say. She didn't comment further. "So, where are we? Did you do any research on this place beforehand?"
Aoko didn't respond immediately, instead surveying her surroundings.
The Aozaki sisters stood at the border between a hill and a grassy plain. In the distance, faint outlines of heavily damaged ruins could be seen through the mist, surrounded by overgrown vegetation.
At first, Aoko thought the plants resembled reeds, but upon closer inspection, she realized she didn't recognize them at all. Beyond the plants, the landscape was dotted with countless gravestones stretching across the hills and plains.
"...You didn't accidentally drop us into some underworld, did you?" Touko suddenly asked.
"What makes you say that?" Aoko gave Touko a meaningful glance. "Sure, there are a lot of gravestones, but it doesn't feel like the underworld, does it?"
"Those gravestones," Touko said, pointing at some nearby, "aren't made of stone. They're individual, slumbering souls."
No way!
Squinting, Aoko focused on the gravestones. Upon closer inspection, she realized they were semi-transparent. Some of the surrounding plants even passed through them or grew right in the middle of them.
"Hmm, still not sure," Aoko said. "Let's check out those ruins over there. The mist might clear up by then."
Unfortunately for them, as soon as the sisters decided to head toward the ruins, a light rain started to fall. The already damp and misty environment became even wetter, forcing them to cast waterproofing spells to avoid getting soaked.
The rain slightly thinned out the mist, allowing Aoko to see a forest behind them. Within the forest, blurry shadows shifted, resembling some kind of wild beasts. Connecting the hill and the forest below was a road that appeared to have been built by some kind of civilized race. The sisters decided to follow the road toward the ruins.
As they descended the hill and reached the road, the mist over the plain began to dissipate. Aoko gazed into the distance and was startled to find certain elements that seemed familiar.
At the far end of the silhouette of a ruined castle stood a towering, sky-piercing tree.
The sight of the colossal tree immediately reminded Aoko of a certain work from her past life. However, the tree didn't look the same as in her memory.
This tree's trunk was black, with golden resin-like liquid flowing down from it. Furthermore, it appeared as though the tree had once been broken in half by some person and had since regrown.
High above, the enormous canopy supported a veil-like structure that shrouded the sky. Even though sunlight filtered through this veil, it gave the entire land an unnaturally dim, yellowish hue.
Did I just jump into the Land of Steel period?!
Aoko felt a twinge of unease as she walked alongside Touko on the road, scanning her surroundings for evidence to confirm or disprove her hypothesis.
"Hey, there's someone over there," Touko said, pointing to the roadside ahead. "Think it's a dead body?"
Following Touko's gaze, Aoko spotted a figure leaning against a stone pillar by the road. It was a soldier wearing a cloak, chainmail, and a helmet reminiscent of Viking warriors.