Fragrance-Free Hair Care for Those Sensitive to Scents

Daiichi Kogyo Seiyaku (Headquarters: Minami-ku, Kyoto; Representative Director and President: Naoki Yamaji) is pleased to announce that its proprietary 'Odor Neutralization Method' has been adopted for Hoyu Co., Ltd.'s (Headquarters: Nagoya, Aichi; Representative Director and President and Executive Officer: Yoshihiro Sasaki; hereinafter Hoyu) fragrance-free brand 'mushu'. This brand was created with a new concept aiming for 'odorlessness', and the shampoo and conditioner are scheduled to be released by Hoyu on Amazon from May 10, 2026.

This product is a fragrance-free hair care developed with scenarios in mind where scent consideration is necessary, such as during changes in physical condition during pregnancy or due to hyperosmia. Daiichi Kogyo Seiyaku participated from the development stage and collaborated with Hoyu on joint development by technically assisting in formula design applying its proprietary 'Odor Neutralization Method'.

Daiichi Kogyo Seiyaku will continue to promote manufacturing that enhances people's quality of life, leveraging its long-cultivated formulation design technology.

## Fragrance-Free Brand 'mushu' Applying the 'Odor Neutralization Method' (Provided by Hoyu)

### About our proprietary 'Odor Neutralization Method'

The 'Odor Neutralization Method' is our proprietary formulation design technology that reduces odor perception by utilizing the interaction between malodorous components and specific fragrance elements, based on the human olfactory receptor mechanism. Unlike masking, which covers odors with strong scents, its characteristic feature is to suppress the perception of odor itself.

Figure 1. Mechanism of perceiving odors

Figure 2. Image of electrical signals as wavelengths

### Technical Points

Applying the design philosophy of this technology, we optimized the overall odor balance of the formulation, including base odors derived from raw materials, without using synthetic fragrances. By carefully examining combinations of multiple raw materials and formulation designs, we aimed to reduce the discomfort of odors during use.
*This technology does not guarantee a complete absence of odor perception.

Figure 3. Odor measurement results for 'mushu' hair care
*Measurement results by our odor sensory specialists using pre-production samples from September 4, 2025.
*The above figures do not guarantee that the product will be perceived as odor-free.

### Development Background

In recent years, while the number of scented products has increased, so has the number of people who find fragrances burdensome due to physical condition, life stage, or living environment. As Hoyu planned the new 'mushu' brand with the concept of 'odorlessness', Daiichi Kogyo Seiyaku participated from the early development stage and realized joint product development by providing technical cooperation from the perspective of odor control and formulation design technology.

### Future Developments

* Product Name: mushu Shampoo / mushu Treatment (Contents: 400mL / 400g)
* Price: 1,780 JPY (excl. tax)
* Release Date: May 10, 2026 (Sunday) (Scheduled to be released on Amazon)

* A new concept aiming for 'odorlessness'. Introducing the fragrance-free brand 'mushu'.
https://www.hoyu.co.jp/news/001352.html

* 'mushu' Product Page
URL https://www.amazon.co.jp/dp/B0GWZR91JH

### [Glossary]

* Proprietary 'Odor Neutralization Method': Odor neutralization is a generally known technical concept that has been around for a long time. The originality in this context lies not in odor neutralization itself, but in the formulation and design tailored for application to general household hair care products and the technical application considering actual use environments.

### Hoyu Co., Ltd. Company Profile

Headquarters: 1-501 Tokugawacho, Higashi-ku, Nagoya, Aichi
Representative: Yoshihiro Sasaki, Representative Director, President and Executive Officer
Founded: 1905 (Meiji 38)
Established: 1923 (Taisho 12)
Capital: 110 million JPY
Number of Employees: 1,080 (as of October 31, 2025)
Consolidated Sales: 52.7 billion JPY (Fiscal year ended October 31, 2025)
Business Activities: Manufacturing and sales of hair color and hair care products
Website: https://www.hoyu.co.jp/

### Daiichi Kogyo Seiyaku Co., Ltd. Company Profile

Headquarters: 48-2 Higashikujo Jonodacho, Minami-ku, Kyoto
Representative: Naoki Yamaji, Representative Director and President
Founded: 1909 (Meiji 42)
Established: 1918 (Taisho 7)
Capital: 8.895 billion JPY
Business Activities: Manufacturing and sales of various industrial chemicals, health foods, and other life science-related products
Website: https://www.dks-web.co.jp/

### [Contact for this release]

Daiichi Kogyo Seiyaku Co., Ltd. Management Division, Strategy Planning Department, Public Relations and IR Department