JAPANESE BODILY SOVEREIGNTY

With winter imminent, we must raise our alert levels to unprecedented heights and confront the coming season. Looking back at 2025, we cannot deny the possibility of a winter where unexpected events occur frequently, as if summarizing a year of intense climate change. While individuals cannot control the climate, that is precisely why we must be more cautious than ever in our daily preparations regarding personal health management—specifically, the extremely delicate yet critical modern task of “Mood Regulation.” This is not the outdated goal of merely maintaining health; it is an urgent crisis management task imposed on every human being. The improvement of this survival capability, through trial and error, will be the foundation for surviving the turbulent 2030s.

In this context, the theme I wish to dig deeply into is the specific ethnic reluctance and weakness we Japanese hold toward the season of “Winter,” and how we have adjusted to it using a survival strategy historically accumulated as “Wisdom of Living.”

From a global perspective, the Japanese lifestyle is often discussed and consumed within the context of aesthetic and spiritual minimalism, such as `Zen` or `Marie Kondo (Cleaning/Tidying)`. However, while that view might have passed in the relatively peaceful pre-pandemic era, looking at the present and the future, I reject that perspective entirely. The true identity of the protocols built by our ancestors was not emotional aesthetics, but pure “Bio-engineering to overcome genetic and geographic disadvantages” within the Japanese environment. So, where did that purpose lie? In this article, I will explore that lost purpose.

To do so, we must first capture the true identity of the risks modern people face with the highest possible resolution. The representative example is the chronic deficiency of “Vitamin D,” primarily generated from sunlight. Recently, depression and mental insufficiency have transcended individual problems to manifest as a human-scale risk, and medical science has long noted Vitamin D deficiency as a hidden primary cause. Vitamin D is not merely a nutrient; it is a substance practically akin to a “steroid hormone” that acts as a command center for serotonin regulation in the brain and immune function.

Here, we must accurately grasp the “specs” of this substance. I say Vitamin D, but a decisive difference exists within it. Broadly speaking, there are two types: “Vitamin D2 (Ergocalciferol)” derived from plant sources like mushrooms, and “Vitamin D3 (Cholecalciferol)” derived from animal sources like fish and generated in the skin via sunbathing. It may seem like a mere difference in chemical structure, but in the biological system of the human being, clinical data overwhelmingly shows that animal-derived “D3” is far superior to plant-derived D2 in terms of blood concentration maintenance efficiency and bioavailability. In other words, the native format for the human OS is “D3,” and other formats may result in conversion losses.

Changing the perspective, the optimal securing and utilization of Vitamin D3, based on individual bodies and environments, serves as a “Shield” to survive modern society. In short, I believe that looking at a person’s awareness of D3 intake serves as an indicator of how they perceive modern society and whether they are prepared to face the turbulent era.

Originally, human beings were designed to generate Vitamin D using a type of cholesterol in the skin as raw material by bathing in ultraviolet rays daily. However, this process—like a plant’s “photosynthesis”—is experiencing a serious bug in the modern age. The required sunbathing time varies greatly depending on latitude, season, and skin exposure. For example, while a few minutes to 10 minutes might suffice at noon in summer, generating the same amount in Tokyo’s winter might require exposing only the face and hands to direct sunlight for nearly an hour. Even more fatal is the fact that UV-B (Ultraviolet B waves), necessary for Vitamin D generation, does not pass through glass. In other words, sunbathing through a window in a heated, bright room generates not even “1 IU” of Vitamin D. For the majority of modern urban dwellers who fall into the indoor lifestyle category, securing the necessary amount through natural generation alone has entered a phase that is physically impossible; moreover, that natural generation amount itself cannot be said to be sufficient for surviving the modern age.

What makes this even more serious is the genetic characteristics held by us Japanese. In fact, research suggests that Japanese people frequently carry variants of the “Vitamin D Receptor (VDR)” and genes that transport/metabolize Vitamin D that are “less effective (inefficient)” compared to Westerners. This means we carry a structural weakness in the system that effectively utilizes Vitamin D synthesized from sunlight. However, an inexplicable paradox exists here. The Japanese archipelago is long from north to south, so climatic conditions change drastically depending on residence.

Specifically, there is the fact that Japanese people have survived for thousands of years in the Tohoku, Hokuriku, and Sea of Japan regions, where winter daylight hours are extremely short and the land is locked away by thick snow clouds for long periods. A point to note is that many of these people, when looking at the Japanese population as a whole, are those who strongly inherited old genes derived from the Jomon period (this does not equal being Jomon people). Unlike the Pacific side or Western Japan like Kyushu, which are warm with abundant sunshine, how did people with “hardware with poor Vitamin D efficiency” survive in harsh environments where they could not acquire sufficient sunlight for nearly half the year?

The concept I propose here is a redefinition of the Japanese `Teinei na Kurashi (Polite Living)`. In modern times, the phrase “Living Politely” is often consumed as mere manners, aesthetics, or a moral slogan. However, when we re-examine this from the perspective of “Bio-hacking” practiced unconsciously by our ancestors, the consistency is spine-chilling. Their lifestyle habits were extremely precise computational processing to forcibly optimize the body (hardware) with poor acquisition efficiency through external supplementation (software). The prime example is Japanese food culture. First, fish eating. Fatty fish like salmon, saury (sanma), and sardines are rare major sources of Vitamin D3 in the natural world. While mushrooms can also be gathered in these regions, unlike animal D3, mushrooms provide plant D2, so they contribute little to Vitamin D activation.

Personally, I am fascinated by the fact that salmon and saury have been fish with high catch volumes in the Sea of Japan side of Tohoku and Hokkaido since ancient times. Although catches of salmon and saury have plummeted recently due to climate change and drastic shifts in nature itself, these fish with high D3 content were major nutrient sources for people in these regions since the Jomon period. The fact that people in Tohoku have consumed salmon as a staple food in diverse ways since the Jomon period shows that it made rational sense for them living under severe winter climate conditions. In addition, we cannot overlook the custom in Japan of eating these fish thoroughly, even down to the bones.

Two months ago, when I visited Murakami City in Niigata Prefecture, which possesses a unique salmon culture, I deepened my understanding of it. In this region, where “Salmon = Kami” is sometimes worshipped, over 100 types of food are created from a single salmon, wasting nothing. This indicates that the people of the Tohoku Sea of Japan side, against a genetic background stretching back to the Jomon period, constructed a lifestyle to compensate for the winter lack of D3 by consuming salmon as a staple food through wisdom of living, and transmitted this generation after generation.

Thus, ancestors compensated for their genetic weaknesses with wisdom utilizing the natural environment, but even more surprising is the technology of “Dried Fish” and “Sun-drying.” This is because the component ergosterol contained in mushrooms like wood ear (kikurage) and shiitake undergoes a chemical change into Vitamin D2 when exposed to ultraviolet rays. The act of deliberately taking the trouble to expose ingredients to the sun is not merely to enhance preservation but is nothing less than an ancient chemical experiment to transform the ingredients themselves into “Edible Sun Supplements.” And worthy of special mention is the combination of “Fermented Food” and “Bone-in Consumption.”

Because Vitamin D is fat-soluble, it has the property of being difficult to absorb on its own. However, by regulating the intestinal environment with Japanese fermented foods like miso, pickles, and natto, and promoting bile secretion, the absorption rate improves dramatically. In particular, Vitamin K2, abundantly found in `Natto`, is a critical partner that exerts a synergistic effect with Vitamin D3; K2 plays the role of guiding the calcium that Vitamin D has brought into the blood correctly to the “Bones” rather than depositing it in the blood vessels (arteriosclerosis). The traditional Japanese breakfast of eating small fish boiled and dried whole (niboshi), consumed alongside fermented foods like natto and miso soup, was not merely a minimalist dietary method, but was actually a perfect nutritional protocol highly perfected long ago to prevent bone fragility and immune decline due to lack of sunlight. It was for “Survival.”