As Yuichi heads back to his dorm after the science class, he is exhausted from the all-nighters he and Niko pulled to prepare for the class. They had been working tirelessly to improve the Hadō #1. Shō (衝, Thrust) spell, and their efforts had paid off. They had successfully created a new version of the spell that was significantly more potent than the original.
When Yuichi arrives at his dorm, he collapses on his futon, still fully dressed, and immediately falls into a deep sleep.
He wakes up later in the day, relieved that it's an off day, giving him the opportunity to rest. After stretching and feeling refreshed, he decides to spend his free time working on a new Kidō spell he had been contemplating. His goal was to create an incantation that could make a space soundproof, providing him with the privacy he might need in the future.
Throughout the day, Yuichi experiments with various incantations and techniques, striving to develop a soundproofing spell. He knows this ability will come in handy, and he's determined to make it work. He tries numerous variations but experiences no success.
As the sun begins to set, Yuichi is on the verge of giving up. However, he decides to make one final attempt. He closes his eyes and concentrates, visualizing the spell he wishes to create. In a surprising turn of events, he hears a faint voice in his mind, his zanpakuto attempting to communicate with him.
Excited by this development, Yuichi maintains his focus, and the voice becomes more distinct. He barely manages to comprehend what his zanpakuto is conveying: the incantation for the soundproofing spell he had been striving to create.
"Silent walls, enclose this space, let no sound escape this place." (開応の降解,声に降解を破る.Kaiō no kōkai, sei ni kōkai wo yaburu)
Yuichi repeats the incantation and experiences a surge of power as the spell takes effect. Upon opening his eyes, he is astonished by the transformation of his room's white walls, which have turned green due to the spell. In a moment of curiosity, he tests the soundproofing by shouting loudly but receives no complaints from neighbors. The spell has successfully rendered his room soundproof, allowing no noise to escape.
Satisfied with his achievement, Yuichi knocks on his neighbor's door to apologize for the noise, and the neighbor, looking puzzled, accepts the apology.
Yuichi reflects on the success of the spell, acknowledging that he should spend more time in the library, as his zanpakuto had played a crucial role in its creation. He also contemplates the need to work on a spell for concealing his Reiryoku, recognizing the potential value of such an ability.
'Looks like it works well and now I won't have to worry about speaking my actual mind in my dorm room at the very least. It's been so long that I almost started believing the persona I showed. I really need to spend more time in the library because if not for my zanpakuto then I wouldn't have been able to create this spell. Now I need to work on a spell for concealing my Reiryoku.'
As he ponders recent events, Yuichi can't help but reflect on his own spiritual power, or Reiryoku. He has always been aware of his potential exceeding that of an average individual, but he's uncertain about the extent of his power.
Recalling the time Yoruichi took him out to eat and his decision to hold back from finishing his food to deceive her, Yuichi also remembers observing how much food Yoruichi and Kensei had consumed. He compared that to what he believed he could eat, finding their eating habits to be similar.
Mei had previously explained to him that Reiryoku levels were divided into six categories:
Basic Spiritual Power or Below Average-class: Common among regular humans.
Average Spiritual Power or Average-class: Typical for low-ranking seated and non-seated members of the Gotei 13 or individuals with lower spiritual power.
Then comes High Spiritual Power or Lieutenant-class: Common among those with an average lieutenant rank and high-ranked seated officers.
Following that is Great Spiritual Power or Captain-class: A level of spiritual power often found among those with an average Captain rank.
Next is Immense Spiritual Power or Advanced Captain-Class: Possessed by seasoned captains and is characterized by its ability to enhance a user during combat and influence the surrounding environment in a controlled manner, allowing the wielder to utilize it to a remarkable extent in combat.
Finally, there is Immeasurable Spiritual Power or Beyond Captain-Class: This level of spiritual power corresponds to those possessing a colossal amount of spiritual power. It is a rare level of power to possess.
He realizes that his Reiryoku level might be much higher than he had previously thought. While he can currently only display Reiryoku slightly above Basic Spiritual Power, he is convinced that he could achieve Great Spiritual Power or even higher. He suspects that the reason he can't currently manifest it is due to his body not being trained to handle it.
He also contemplates the challenges he's faced in hearing the voice of his zanpakuto. He figures that this, too, may be a result of his untrained body and high Reiryoku level. He acknowledges that reaching his full potential will require extensive training and hard work, but he is determined to do whatever it takes to become stronger.
To Yuichi's knowledge, there are three ways to quickly increase his Reiryoku. The first involves old-fashioned, rigorous training. This method can be used by anyone to boost their Reiryoku by strengthening their body to contain more spiritual power, and it's the approach currently provided by the academy.
The next method involves the Hougyoku, an item that grants strength to those who seek it. It seems to adapt to the user's needs or desires in any given situation, making it an effortless way to boost Reiryoku. However, as of now, only two individuals can create the Hougyoku: Aizen and Urahara, making this option currently unavailable.
The third method entails engaging in a challenging battle, suffering heavy injuries, and subsequently receiving healing. As a result, the individual becomes significantly stronger than before. Many soul reapers undergo this process, as seen with characters like Ichigo, who progressed from being defeated by a base-level Ulquiorra while using his hollow mask to defeating the same Ulquiorra with his hollow mask a few hours later.
Yuichi reflects on his current approach (option #1) and rules out option #2 due to its inaccessibility. He also considers the drawbacks of option #3, as it can be dangerous and doesn't come with the plot armor that some characters, like Ichigo, possess. Instead, he contemplates an alternative path to gaining strength: becoming a Visored. This would require him to anticipate when Aizen makes his move and get involved toward the end of the process to avoid fully transforming into a hollow.