The day after returning from the investigation trip, Jin led Elsa, Saki, and Hanna to the Predecessor's study.
Reiko led the way.
"I wonder how many years it’s been since I was last here..."
Walking down the corridor, Jin felt a sense of wonder.
He had first awakened in this world, met the automata that was Reiko’s original form, and been shown the way to the Predecessor’s study. Then, he had opened that door—the one the previous automata had not been allowed to enter.
Inside, he had seen shelves overflowing with books, a simple but sturdy desk and chair, and a book and crystal ball resting on top.
Immersed in his memories, Jin reached for the door handle.
"Wait... what?"
At that moment, he felt a light wave of dizziness.
"This is..."
Back then, he had been thrown off when he tried to push a door that opened by pulling, but that same lapse in focus had happened again. Looking back at Elsa and the others, he saw they were all wearing vacant expressions.
"Just as I thought."
Jin surmised that there was some kind of mental defense barrier here. Having gained so much experience in this world of magic, his intuition was much sharper than when he was first summoned.
"It's likely a final layer of protection to ensure her privacy."
Jin instructed Laojun to activate the Magic Barrier function on the Fellowship Bracelets worn by the three girls. He deployed his own Magic Barrier as well. With this, mental magical effects would no longer work on them.
"..."
"Huh?"
"Was I... asleep?"
The three of them seemed to snap back to their senses.
"Yeah. I just realized it, but there seems to be a mental defense barrier around here. It was making everyone feel lethargic."
As he explained, Jin began examining the door.
"Found it. This is..."
A magi-formula was engraved on the back of the door. It was a sequence Jin had never seen before.
"There’s text here, too. Let's see..."
Jin read the characters slowly.
"'I could not analyze this magi-formula myself, but it functions by reducing the interest of those who approach.' Reiko, did you know about this?"
Reiko shook her head apologetically.
"No, Father. I didn't. Though it’s possible I simply don’t remember."
The latter was likely the case. The automata that preceded Reiko had cared for the Predecessor and guided Jin even with this barrier active.
"To think such a magi-formula exists..."
Jin recognized the characters. They were likely the script used by the Progenitors. It was the prototype for the writing currently used in Ars. The difference was roughly like that between Greek and Latin; Jin could only barely manage to read it.
"The Predecessor must have found this magi-formula somewhere and copied it down in its entirety."
From the parts he could read, he estimated its effects were similar to the Seduce spell, but without any lingering side effects; it simply lowered one's curiosity toward this specific location. It seemed to belong to the same family of magic as the Hide spell—a spell that erased one's presence but broke if the user made a noise or was attacked.
He further surmised that this barrier worked on automata and golems as well. During his travels through the Kingdom of Elias with Elsa and Reinhard, Reiko had been unable to sense a bandit wearing an amulet with a Hide effect.
However, once someone became consciously aware of it, the effect would break. When they had first visited, the previous automata was intimately familiar with the study, so she had guided Jin without hesitation. Even then, Jin had been affected enough to be confused by which way the door opened.
This barrier is incredibly useful. If we set this up around Hourai Island, the chances of being discovered will drop even further, Jin thought.
"Is that why even you didn't remember this place until recently, Jin-nii?"
Elsa’s voice pulled Jin out of his thoughts.
"It seems so. After leaving this room back then, it felt like I just didn't have any reason to come back."
"Why would the Predecessor set up a barrier like this?"
Saki tilted her head. Jin offered his theory.
"Essentially, she didn't want anyone near her room. The Predecessor must have become quite the recluse in her final years."
"..."
Based on the records he'd seen so far, the Predecessor had a bright personality. Jin wondered what had happened to her. Part of him wanted to know, while another part felt it might be better left a mystery.
They couldn't stay in the corridor forever. Jin looked up, took Reiko’s hand, and stepped into the room. The others waited in the hallway for a moment.
"This is my second time in the Predecessor’s study."
Just as before, the room was flooded with light the moment he stepped inside.
"I was so overwhelmed last time that I didn't get a chance to really look around."
Jin surveyed the room. The simple but sturdy desk and chair remained exactly as they were. And the bookshelves were still packed tight.
"Wait... what?"
When he picked up one of the books, he found the pages were blank. They were dummy books. He wondered why she had gone to such lengths.
He reached out and lightly touched the bookshelf. He felt the shelf shift slightly.
"That's strange. A bookshelf this heavy shouldn't move that easily."
Upon closer inspection, he found the reason. The bookshelf was designed to slide sideways. Jin slowly moved it.
"Whoa."
Hidden behind the shelf was a single door. The name "Adriana Barbora Tsetse" was inscribed there in gold lettering.
"Is this her true private study?"
Jin gently opened the door. Inside was a similar room. Or rather, the outer room was a dummy, and this was the genuine one. It held similar heavy bookshelves, a desk, and a chair. But there was one difference.
"A paper crane..."
In the center of the bookshelf sat a transparent crystal case. Inside was a single, aged, yellowed paper crane.
"Father, is this the one Mother received from Grandfather?"
Reiko asked as she saw the paper crane the Predecessor had cherished. The version of Reiko from back then likely remembered it, but that memory had been lost when her original control core was damaged. In that sense, this visit was deeply significant for her.
"Yes. I’m almost certain of it."
"It was Mother’s treasure."
How many years had she spent with it since receiving it from Shuuki, and how long had it sat here? Over a thousand years. It was clear just how much Adriana Barbora Tsetse had valued it.
Jin and Reiko were lost in thought for a moment before remembering that Elsa, Saki, and Hanna were still in the corridor.
"Ah, sorry. Everyone, please come in."
"Pardon the intrusion."
"Pardon the intrusion."
"Pardon the intrusion."
The three of them entered with quiet, respectful voices, which made Jin happy.
"So this was the Predecessor’s study."
"The room of the previous Magi Craft Meister."
"She was like Onii-chan's teacher, right? It's thanks to her that I was able to meet Onii-chan."
Hanna murmured more to herself than anyone else, then offered a silent prayer toward the paper crane. Elsa and Saki followed her lead. Jin closed his eyes as well, and Reiko joined them.
"Thank you, everyone."
After about a minute, Jin opened his eyes.
"Now then, this is the Predecessor’s real study. I expect there are records of some kind on these shelves."
"I agree, Father."
There were numerous books with gold lettering on black leather spines. About half were written in Japanese—though using only hiragana.
Shuuki-san must not have taught her kanji. Or perhaps there was so much else to learn that he couldn't get to it, or it was just a low priority.
Either way, it made sense why the Predecessor's magi-formulas didn't use kanji.
He picked up a book. It must have been protected by preservation magic, as it looked as fresh as if it had just been made. The fact that the room was magically sealed likely helped.
"This must be the record the Predecessor left behind."
The spine read: My Footsteps, Volume 1. "Footsteps" likely referred to a diary of her life. It was held shut by a matching leather strap to prevent it from opening easily. If he undid the clasp, the diary would be opened... and yet.
Jin hesitated.
"Father, what is it?" Reiko asked, curious.
Jin made a slightly troubled face.
"I just feel like I’m prying into someone else’s private thoughts."
"In that case, Father, let me. Surely it would be forgiven for a daughter to look at her mother’s diary."
"I suppose so."
It was a bit of a stretch, but it made Jin feel better. He handed the diary to Reiko. Reiko took it and was about to undo the clasp when she noticed the text written there.
"Father, there’s a note here. 'I permit only the one who inherits my will to open this.'"
"I see."
Jin took the diary back from Reiko, undid the clasp, and slowly opened the cover.
"...The beginning seems to cover the same journey of the Magus we’ve already seen," Jin said as he flipped through the pages. "Ah, it mentions Shuuki’s passing here. From this point on, it’s unknown territory."
'Having buried my beloved father, Shuuki Tsetse, I decided to set out on a journey alone.'
Jin began to read the words aloud in a soft voice.