After returning home from Kyoni Animation Co., Ltd., Kamiyā Yuu spent the evening flipping through the 'Complete Guide to Key Animation Techniques' that Uehara Etsuki had given him.
This 'Complete Guide to Key Animation Techniques' was an early foundational classic for animators in this world. Many renowned key animators had mentioned that it was this very book that led them into the industry. However, as time passed, much of the knowledge recorded in it became outdated and was gradually abandoned. Nowadays, aside from being available online, it is nearly impossible to find in physical stores.
The copy Kamiyā Yuu received, however, was different. It embodied three years of Uehara Etsuki's effort and dedication, documenting her entire journey from knowing nothing about animation to becoming an outstanding key animator. The bookmarks alone numbered in the hundreds, each one filled with her detailed understanding of the techniques described.
Running his hand over the book's cover, Kamiyā Yuu could feel how the sheer number of bookmarks had expanded its thickness by more than half, almost comparable to a Chinese dictionary from his previous life.
—Damn, if this were before I got transported here, I probably wouldn't even bother opening something this thick.
He chuckled and carefully placed the book on his desk before opening it. The handwriting on the bookmarks was neat, resembling traditional Song-style Chinese calligraphy—fluid and graceful.
"That Uehara-sensei… no matter how you look at her, there's not a single flaw. If she had the 'closed-eyes' character trope, it would fit perfectly." Seeing the calligraphy-like notes, Kamiyā Yuu couldn't help but sigh in admiration. Since meeting Uehara Etsuki, he hadn't found even the slightest imperfection in her.
The content of the book was extremely comprehensive, covering every aspect a key animator needed to learn. From muscular men with bulging physiques to delicate, pitiful girls; from sci-fi space opera settings to classical Roman-style architecture—it detailed everything, clearly marking key points to pay attention to. Combined with Uehara Etsuki's annotated bookmarks, it opened Kamiyā Yuu's eyes. Compared to most animation materials publicly available online in his previous world, this book was on an entirely different level.
Kamiyā Yuu became completely absorbed in the 'Complete Guide to Key Animation Techniques' for the entire night, intending to imprint all its contents into his memory. Once asleep, he would enter his consciousness space and use his extraordinary learning ability to fully digest it. In this regard, Uehara Etsuki had underestimated him—thanks to the enhanced learning ability granted by his consciousness space, it wouldn't take him long to master everything in the book.
"Yuu, are you going to be busy again tomorrow?" The gothic girl lying lazily on Kamiyā Yuu's bed asked softly. Her cool gaze rested on the laptop by the bedside, her slender fingers absentmindedly scrolling the mouse. Not far away, Kamiyā Yuu sat in his chair, completely focused on the book in his hands.
Sunday was one of the few official holidays for most people in Japan.
Without looking up, Kamiyā Yuu replied casually while memorizing the contents, "No, the animation schedule at the company has caught up."
"I see." A faint smile appeared on Kamiyā Sora's pale lips. She hugged Kamiyā Yuu's pillow and buried her face slightly into it, the familiar scent bringing her comfort. A faint blush appeared on her fair skin.
"Then, Sora, do you want to go anywhere tomorrow? I can spend the whole day with you—maybe at an amusement park or shopping at the mall. The company should pay salaries next week, and since I've handled quite a few corrected cuts lately, it should be a bit higher than usual." Kamiyā Yuu paused his reading and turned to look at her, speaking gently.
The girl, who carried an ethereal elegance, wore a pure white Gothic nightdress. The soft, thin fabric couldn't fully conceal her jade-like skin. White ribbons were tied around her slender waist and arms, holding the loose, ruffled garment in place, giving her every movement a delicate, youthful charm tinged with a hazy beauty.
Lying on the bed and lightly kicking her feet, Kamiyā Sora kept her eyes fixed on the laptop screen, avoiding his gaze as if reluctant to meet it. In a calm, steady voice, she replied, "No need. Staying home is fine." It was clear she was satisfied with his response.
This simple exchange was their most familiar way of interacting—often, they understood each other without needing to say much at all.
Kamiyā Yuu smiled and turned back, but his interest in the book before him had already faded. His thoughts drifted to a certain "little sister" anime from his previous world.
—It's about time I concluded. No surprises—it's heading in the direction of 'Yosuga no Sora.' For now, maintaining the balance is the best approach.
The current Kamiyā Yuu was no longer the oblivious person he once was. No matter how composed Kamiyā Sora appeared, he could clearly sense the changes in her over time. Her attitude toward him was far from that of a normal younger sister. No ordinary sister would show such an almost obsessive attachment and possessiveness toward her brother—permeating every aspect of daily life, as if trying to engrave her existence into his very consciousness.
Kamiyā Sora herself was likely aware of this—perhaps she had known for a long time. But being even more mature than Kamiyā Yuu in certain ways, she simply didn't care about external constraints. Morality, public opinion—none of it mattered to her. The only thing she wanted was Kamiyā Yuu, someone who would give everything for her.
So what would Kamiyā Yuu, an ordinary person, think? Would he accept her distorted feelings and the life she desired? Knowing his personality, Kamiyā Sora already had the answer, yet she still observed him with a conflicted heart—hoping that one day he would realize everything and willingly give up all else for her.
—That girl Sora… should I call her innocent, or incredibly perceptive?
Kamiyā Yuu rubbed his temples in frustration. Until he fully confirmed his own identity, he had no intention of "visiting German orthopedics." Yet as he became more integrated into this life, part of him no longer wanted to uncover the truth. He couldn't deny that he felt fear—fear that the answer wouldn't be what he hoped for. Or perhaps… he was simply enjoying this dangerous balance on the edge of morality.
At this moment, Kamiyā Yuu found himself envying the protagonist of 'Yosuga no Sora'—that version of "Yuu"—who dared to respond to his sister's twisted feelings without hesitation and abandon everything for her. The more mature a person was, the more they understood why they should retreat in the face of such a choice. Kamiyā Yuu clearly understood the fundamental difference between himself and that "Yuu."
He might be a sister-lover—perhaps he could even give up his life for Kamiyā Sora—but he lacked the courage to abandon the entire world for her.
Now reborn into this new life, Kamiyā Yuu had set himself grand ambitions. He could give them up for Sora—but unless forced into that choice, he wouldn't make such a decision lightly.
—Maybe this is just a common problem for people who get transported to another world. Back then, if I saw this kind of development in a manga, I'd put on a "rational" face and say, "What's there to complain about?" Damn it… Anyone who says that should go home, look at their own sister, and ask themselves if they really have the resolve to act on it. Do they really have the guts for "German orthopedics"? Out of 1.3 billion people, only one guy actually had the nerve to go through with it.
Kamiyā Yuu's eyes grew unfocused as his thoughts drifted aimlessly, no longer paying attention to the pages of the animation book he was flipping through.