Are Plant-Based Ingredients Dangerous!? What OSAJI Defines as "Truly Safe Cosmetics"

The market for natural and organic cosmetics has exploded in recent years, with a flood of products formulated with plant-based ingredients. But their actual “safety” is a constant subject of debate.

This brings us to OSAJI, a cosmetics brand that champions "truly safe cosmetics" by developing products grounded in dermatology. We sat down with founder and representative Masakazu Shigeta to discuss his perspective on the “safety myth” surrounding plant-based ingredients, his dedicated approach to development, and his vision for skincare that enhances the skin's inherent power.

It All Started with a Question About "Supposedly Safe Cosmetics"

You might think of OSAJI as just another “natural cosmetics” brand. But the truth is, instead of focusing solely on natural ingredients, they develop their products based on dermatological science.

“The journey of OSAJI began when my mother developed PTSD following a car accident, leading to a severe eczema outbreak. She had always used and deeply trusted a brand built on the concept of ‘edible cosmetics,’ but suddenly, even those products became unusable.

Listening to her distress, I couldn't help but wonder, ‘Why can't she use cosmetics that are supposedly safe enough to eat?’ My uncle, a dermatologist, sent us numerous samples for sensitive skin, but the only product my mother could tolerate was a very simple one made with just four or five ingredients. That's when I thought, ‘I could probably make something like this myself.’ I ordered the raw ingredients and began developing formulas right in my kitchen.

My uncle also mentioned that hot springs can sometimes help people with stubborn skin conditions, so I added hot spring water to my simple formula to create a prototype. While I quickly made something usable for my mother, it took a full six months to create a product that I was genuinely happy with.”

What began in a home kitchen for his mother's sake has grown into OSAJI, a brand now supported by many people with skin concerns. Today, it has stores in department stores and commercial facilities across Japan and has even started expanding overseas as of 2024.

'Safe to Eat' Does Not Equal 'Safe for Skin'

While many brands on the market claim to be based on dermatology, what specifically does OSAJI mean by “dermatology-based cosmetics”?

“As I was creating cosmetics to help with my mother's condition, I dove deep into dermatology. I studied why skin turns over, how the barrier function is built and operates, and what kinds of bacteria live on our skin and their roles. My research led me to a firm conclusion: ‘safe to eat’ does not mean ‘safe for skin.’ I also discovered that it’s actually better if cosmetics don't penetrate the skin.

At OSAJI, instead of aiming for special effects, we prioritize correcting the body's natural physiological functions—which can be weakened by air pollution, low humidity, or even over-washing—based on dermatological principles. The truth is, many people are unintentionally weakening their skin by following misinformation they find in the media and on social media.

Because so much false information has become accepted fact thanks to advertising claims, we feel it's our responsibility at OSAJI to share accurate, science-backed information.”

So, what does OSAJI consider to be "truly safe cosmetics"?

"When we think about safety, we believe that protein-derived allergies are far more frightening than temporary stinging or tingling sensations. That temporary irritation is caused by low-molecular-weight compounds and goes away once you stop using the product, but protein-derived allergies can sometimes be life-threatening.

There have been cases where protein-derived ingredients in cosmetics trigger anaphylaxis, leading to a situation where the person can no longer eat the food that caused it. Even if it's not a matter of life and death, cosmetics should never diminish a user's quality of life.

That's why you can't make a simple right-or-wrong judgment based on whether something is 'naturally derived or plant-derived.' Even with nut oils, just because they contain high-molecular-weight proteins doesn't mean they're all off-limits; you have to grasp the characteristics of each ingredient to make an informed decision.

At OSAJI, we don't just check for the presence of specified allergenic ingredients. We meticulously verify 'for what purpose, how, and at what concentration' we use each ingredient in our cosmetic formulations. This also varies depending on the application area—be it the face, body, or around the eyes—so each requires its own research.

When choosing cosmetics, I believe it's crucial to look beyond simple factors like whether a product is natural or plant-derived, tested on animals, or paraben-free. It's also important to understand the safety standards and testing details that the manufacturer presents."

OSAJI's skincare is developed with a focus on skin-beautifying bacteria and the skin's barrier function.

"The balance of resident skin flora is incredibly important for healthy skin. When you have enough skin-beautifying bacteria and a healthy balance of various microbes, they break down sebum and convert it into beneficial short-chain fatty acids (like succinic and butyric acid) and glycerin. This process helps maintain the skin's surface at a slightly acidic pH.

This slightly acidic environment plays a key role in preventing the growth of pathogens and viruses. OSAJI's skincare is formulated with an emphasis on creating conditions that allow these beneficial bacteria to function properly.

Furthermore, we believe the skin's barrier function is best when it's in a 'balanced' state. The strength of the barrier function is determined by the thickness of the stratum corneum (the outermost layer of skin), but since this layer can appear grayish, an overly thick barrier can make the skin look dull. When the barrier function is compromised, allergens like pollen and other external factors that wouldn't normally enter the body can cause skin troubles like inflammation.

If the skin's barrier function is optimally balanced, skin texture becomes smoother, clarity improves, and pores become less noticeable. When your skin is in this state, it can look beautiful with just a light application of foundation."

"True Safety" for All: OSAJI's Mission and Vision for the Future

OSAJI also develops makeup products, which reflect the company's unique philosophy.

"Our goal isn't to make products 'for sensitive skin,' but rather to create 'inclusive' products. OSAJI aims to deliver 'truly safe cosmetics' to the world—not just to reassure people with sensitive skin, but to create products that anyone, regardless of skin type or physical condition, like visual impairment, can use and find joy in skincare and makeup.

Even for those with extremely delicate skin, makeup can often be used if the pigment components don't come into direct contact with the skin, so at OSAJI, we employ techniques like coating the pigments. It's also important for makeup to provide skincare benefits, so we're also aiming to incorporate effects that help repair the barrier function. We're still in the research phase, but our ultimate goal is to create products that actively improve your skin the more you use them."

What kind of feedback has OSAJI received from its users about products based on this philosophy?

"We've received a lot of positive feedback, not just from people with sensitive skin who are delighted with our products, but also from those who say things like, 'My skin isn't sensitive, but it's in great shape now,' and 'I struggled to find cosmetics that didn't cause irritation, but OSAJI works for me!'

Through our products and the information we share, we feel that our users are embracing our belief that 'the essential skincare routine is the same for everyone, regardless of skin type.'"

To ensure they can continue to provide these products sustainably, OSAJI is also looking ahead to the future of the cosmetics industry.

"New products and ingredients are being developed every day. While scientific progress is vital, it's also crucial for cosmetics to be sustainable in the long run.

Right now, Japan imports over 70% of its cosmetic ingredients. With the Southeast Asian cosmetics market now larger than Japan's and continuing to grow rapidly, we can't ignore the possibility that we might face a shortage of imported raw materials in the future.

Given this situation, we at OSAJI want to focus our efforts on creating cosmetic ingredients using resources from within Japan. This isn't just about clean beauty; we aim to harness the power of our domestic agriculture to produce our own raw materials.

Right now, we're working to develop our own unique ingredients, all while scientifically validating their effects on the skin—something we've always prioritized. We're currently testing how much of a product, like hair oil, we can create using self-sufficient, domestically sourced ingredients."

At the heart of OSAJI's product development lies a deep-seated passion for dermatology, born from founder Shigeta's personal experiences, and a powerful conviction to "deliver truly safe products to everyone." We look forward to following OSAJI's ongoing challenge to create sustainable cosmetics by harnessing Japan's own natural resources.