Itoguchi, Silk Skincare Brand, Launches 'Fermented × Midori-mayu Silk' Booster Serum 'Midori-mayu Fermented Silk Booster'

Itoguchi f Midori-mayu Fermented Silk Booster

Kimono Brain Co., Ltd. (Headquarters: Tokamachi City, Niigata Prefecture; President: Matsuo Okamoto) announces the launch of a new line under its silk skincare brand 'Itoguchi (Itoguchi)'—'Itoguchi f'—centered on its proprietary 'fermented silk' technology. The first product, the 'Midori-mayu Fermented Silk Booster (pre-serum),' will be released on Sunday, June 21, 2026.

After over five years of public-academia-industry collaboration, Itoguchi—long based in Tokamachi, Niigata, the 'city of kimonos'—has developed a globally unique※1 raw material: 'fermented × Midori-mayu silk'※2. Silk is known as a natural material most similar to human protein. This new cosmetic ingredient, developed exclusively by Itoguchi, combines silk components from Midori-mayu (hydrolyzed sericin) with sugar (pineapple juice) and is carefully fermented using plant-based lactic acid bacteria.

Launching on June 21, 2026 as the first product under [Itoguchi f], the 'Midori-mayu Fermented Silk Booster (pre-serum)' luxuriously blends naturally derived lactic acid produced through fermentation and silk components with amino acid composition similar to the skin's natural moisturizing factor (NMF). This is the first drop that gently softens the stratum corneum and enhances the absorption of subsequent skincare products.

※1 In-house developed raw material by fermenting silk components derived from 'Midori-mayu' raised in our sterile silkworm farming facility using lactic acid bacteria (based on internal research)

※2 Lactococcus / (Hydrolyzed Sericin / Pineapple Fruit Juice) Ferment Filtrate (skin conditioning, moisturizing)

■ New Line 'Itoguchi f (Itoguchi F)' Featuring Fermented Silk as Key Ingredient

Silk has recently been called 'the second skin' due to its high skin affinity. As the natural material closest to human protein, it integrates with the skin and functions like a part of it.

Itoguchi, with over 40 years of experience working with silk in Tokamachi, Niigata, has systematized its unique formulation philosophy—'Midori-mayu × Fermentation × Silk Science'—through more than five years of public-academia-industry collaboration. This is Green Silk Protect™.

The 'f' stands for 'Fermented'.

Itoguchi f is a new line born from both a proprietary raw material※ combining fermentation and silk, and the systematization of silk science through Green Silk Protect™. It transforms silk from a material that 'approaches the skin' into one that 'blends into the skin'.

Itoguchi f (Itoguchi F) Brand Logo

※ In-house developed raw material by fermenting silk components derived from 'Midori-mayu' raised in our sterile silkworm farming facility using lactic acid bacteria (based on internal research)

■ Itoguchi's Original New Ingredient [Fermented Sericin※]

INCI Name: Lactococcus / Hydrolyzed Sericin / Pineapple Fruit Juice Ferment Filtrate

Japanese Name: Lactococcus / (Hydrolyzed Sericin / Pineapple Fruit Juice) Ferment Filtrate (skin conditioning, moisturizing)

A new cosmetic ingredient developed exclusively by Itoguchi: hydrolyzed sericin extracted from rare 'Midori-mayu silk' is combined with pineapple juice and carefully fermented using plant-based lactic acid bacteria. Naturally derived lactic acid produced during fermentation and silk components resembling the skin's moisture factors (NMF) gently soften the stratum corneum.

Midori-mayu Fermented Silk Image

※ In-house developed raw material by fermenting silk components derived from 'Midori-mayu' raised in our sterile silkworm farming facility using lactic acid bacteria (based on internal research)

■ Product Overview

Midori-mayu Fermented Silk Booster

Brand Name: Itoguchi f (Itoguchi F)

Product Name: Midori-mayu Fermented Silk Booster (pre-serum)

Release Date: Sunday, June 21, 2026

Volume / Price: 30mL / ¥3,960 (tax included)

Available at: Silk Life Laboratory Official Online Store

Silk Life Laboratory Official Online Shop on Amazon

Loft large stores (Sendai, Ikebukuro, Omiya, Kawasaki, Kichijoji, Chiba, Ginza, Futako-Tamagawa,

Shibuya, Yokohama, Umeda, Kyoto, Kobe, Tenjin, Sakae)

Ethical&SEA Hankyu Umeda Main Store

Luxuriously formulated with Itoguchi's original silk ingredients 'Fermented Sericin※1' and 'Hydrolyzed Sericin※2' up to the maximum limit※3 that does not compromise the sensory experience. A rich base formulation that does not rely solely on 'water' gently softens the stratum corneum and enhances the skin compatibility of subsequent skincare products.

Formulated with 99.7% naturally derived ingredients, free from ethanol, parabens, synthetic fragrances, synthetic dyes, and petroleum-based surfactants—crafted for authenticity and skin compatibility.

Official Online Store: https://silklifelab.com/

※ The product page for 'Midori-mayu Fermented Silk Booster' will be launched on the release date (June 21).

■ 3 Product Features of 'Midori-mayu Fermented Silk Booster'

1. '3-Step Formula' that loosens the stratum corneum※4 and invites subsequent skincare

Softening: Naturally derived lactic acid generated during the fermentation process of Fermented Sericin※1 loosens dry, hardened keratin.

Priming: Skin-conditioning ingredient Willbride※5 boosts delivery of beauty ingredients to every corner of the stratum corneum.

Hydration Pathway: Moisturizing ingredients such as Hydrolyzed Sericin※2 and Glyceryl Glucoside help maintain the skin's moisture balance and provide hydration.

2. Luxurious cocktail formula combining trending 'skin-conditioning ingredients' and 'barrier protection'

Skin Conditioning: Glutathione × Vitamin C derivative※6 refines skin texture, while Niacinamide adds firmness to the skin.

Protection: To maintain healthy skin, Royal Biosite※7, focused on soothing irritation, and RejuiA®※8, with high moisturizing power, are added.

This formula not only conditions the skin but also prevents moisture loss.

3. The natural scent of the ingredients

Instead of masking with fragrance, the product highlights the slightly acidic, natural scent unique to fermented raw materials from plant-based lactic acid bacteria. This unique aroma is proof of Itoguchi's dedication to authenticity—high concentrations of rare ingredients with unnecessary additives stripped away.

※1 Lactococcus / (Hydrolyzed Sericin / Pineapple Fruit Juice) Ferment Filtrate (skin conditioning, moisturizing)

※2 Hydrolyzed Sericin (moisturizing), ※3 Maximum limit in our formulation, ※4 Loosening bonds between corneocytes

※5 PEG/PPG/Polybutylene Glycol-8/5/3 Glycerin, ※6 Ascorbyl Glucoside

※7 Hydrolyzed Royal Jelly Protein, ※8 Polyquaternium-51

■ Kimono Brain Company Overview

Kimono Brain Head Office Factory

Founded around 50 years ago in Tokamachi, Niigata, Kimono Brain Co., Ltd. holds the top market share in Japan for 'kimono aftercare' services such as stain removal and tailoring. Since its founding, the company has upheld SDG principles, including gender equality and employment of people with disabilities. Today, to support its region—a potential disappearing city—it has commercialized the world's first 'sterile, artificial feeding, year-round silkworm farming'. "mi