The reason Onmyoji must register their shikigami isn't arbitrary—it's a rule painstakingly established over many years by the major Onmyo families.
Everyone knew that Onmyoji could command shikigami, and in some ways, shikigami functioned as a personal combat force. Naturally, some Onmyoji used their shikigami to perform tasks they themselves found inconvenient or distasteful.
Years ago, one well-respected Onmyoji, admired in public, secretly used his shikigami for forbidden deeds. When this scandal came to light, it shook the entire exorcist community. Ever since, the Onmyo world agreed that all shikigami used by legitimate Onmyoji must be registered.
This way, if a shikigami ever caused trouble, the exorcist authorities could immediately identify its true master through the registered records, curbing reckless or illicit use.
Of course, while most exorcist families had this rule on paper, few actually registered all of their shikigami. To an Onmyoji, shikigami were extensions of their power, and most would be reluctant to reveal their full strength to others. Some families did conceal their most powerful shikigami, though generally unregistered shikigami weren't used in public. According to the rules, only officially registered shikigami were recognized by the exorcist community. Any Onmyoji caught using an unregistered shikigami in combat would be held accountable.
"Now, please present your shikigami," the Shikigami Dormitory teacher instructed, "and provide a brief description of their race and spiritual power. As for their abilities… that's your choice. We respect the secrets of an Onmyoji's power."
The teacher led Ren Kuroda to a large hall, where a magic circle awaited in the center. This system only measured spiritual power levels and automatically recorded each shikigami's information into the Shikigami Registry—no more, no less.
"Nurikabe, Spider Princess, you two, step forward and register."
Yuto gestured, and his shikigami obeyed. Nurikabe lumbered ahead first, followed by Spider Princess, the beautiful maid shikigami. A ripple of surprise ran through the gathered students—many had assumed the voluptuous maid was merely Yuto's servant, not one of his shikigami.
Using a shikigami as a maid? The students whispered in admiration. Yet they didn't know: Spider Princess's choice to wear a maid outfit wasn't Yuto's idea—it was hers.
When she first arrived in this world, the vast cultural differences between it and the Demon Slayer world confused her. The fastest way to understand human norms was through television and the internet. There, she discovered the archetype of a "maid" and immediately resonated with the concept. A maid dedicated herself entirely to her master, meticulously caring for their every need. Spider Princess believed she could fulfill this role perfectly for Lord Yuto.
From that day forward, she fashioned a maid outfit from her own silk and wore it proudly. Being a maid allowed her to remain inseparable from Yuto. She also learned online that young men seemed oddly receptive to maids—a phenomenon the internet dubbed "uniform fetishism."
As Nurikabe and Spider Princess entered the magic circle, the registration teacher studied the data Yuto had provided, frowning.
"They are your shikigami," he said carefully, "but they haven't signed a formal shikigami contract with you? That explains something—I sensed demonic energy from them during battle rather than the usual shikigami spiritual signature."
Yuto scratched his head. Of course they hadn't signed a contract; he didn't even know how. And even if he had, he hadn't intended to bind them—he promised when they joined him that their bond would be one of "partners," not "master and servant."
"It's not that they can't be registered," the teacher said gently, "but are you sure you want them to remain like this? Without a shikigami contract, they're essentially wild yokai. Without restraint, the risk of them turning on their master is high."
It was common knowledge that forming a shikigami contract consumed an Onmyoji's spiritual power each time the shikigami was summoned. The number of shikigami a master could command simultaneously was often used as a measure of their strength. In the past, some Onmyoji had tried to circumvent the system: when a yokai chose to submit, they didn't form a contract, allowing the yokai to retain its full form. This spared the master from expending spiritual energy—but such arrangements often ended tragically.
Once yokai sensed an opportunity for revenge, they didn't hesitate. Those with a conscience fled; the vengeful killed. After all, who enjoyed being a tireless laborer, bound year-round?
"It's fine," Yuto replied coolly. "Since registration is possible, let's do that first. As for a shikigami contract, I've just transferred here and know almost nothing about Onmyoji techniques. I'll formalize the contract later, once I've learned enough."
The teacher could only nod. In all his years at the Shikigami Bureau, he had never met an Onmyoji like Yuto—someone with no knowledge of contracts, yet capable of controlling powerful yokai willing to submit.