Why an environmental venture from Okayama made a fuel additive that became an Amazon bestseller
Tsugi no Tomoshibi Co., Ltd., an environmental venture from Okayama, achieved Amazon bestseller status with its diesel fuel additive "SUSU-GOROSHI" series. Their unique business model, which directly incorporates customer feedback into product development and advertising, is the key to their success.
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- 📰 Published: May 3, 2026 at 05:15
- 🔍 Collected: May 2, 2026 at 21:01
- 🤖 AI Analyzed: May 2, 2026 at 21:04 (2 min after Collected)
Tsugi no Tomoshibi Co., Ltd., headquartered in Okayama City, Okayama Prefecture, is a circular economy environmental venture that purchases and regenerates discarded commercial vehicle parts (DPF filters and SCR catalysts) to recover rare metals.
The company's diesel vehicle fuel additive "SUSU-GOROSHI" (Soot Killer) series ("Kiwami 500", "Kiwami 300", "Kiwami 200") achieved bestseller status in the Amazon "Automotive Diesel Additives" category on April 19, 2026. This achievement is not due to a single initiative.
It is the result of three factors working simultaneously: a development system that directly incorporates customer feedback into product improvements, an advertising strategy integrated both on and off Amazon, and a business structure that self-directs the entire value chain excluding manufacturing.
This model, distinct from the traditional Japanese manufacturing industry's reliance on division of labor and trading company distribution, illustrates a concrete vision for the role local ventures can play in decarbonizing industrial sites towards the realization of GX (Green Transformation) and Carbon Neutrality 2050.
## Societal Background: The "Common Sense of Division of Labor" in Manufacturing and its Limits
Japanese manufacturing has developed a sophisticated system of division of labor. Specialized organizations handle product planning, R&D, manufacturing, logistics, sales, and marketing, historically achieving efficiency and quality improvement in each process. However, this structure has inherent challenges from the perspective of adapting to environmental changes.
Information tends to be altered or delayed as field issues pass through multiple organizations before reaching product planning. In distribution via trading companies and agencies, end-user voices rarely reach manufacturers directly. When advertising and PR are outsourced to external agencies, communication often lacks on-the-ground knowledge.
The GX policy and circular economy promoted by the government necessitate a cycle where companies with on-site challenges design solutions themselves, deliver them directly to the market, obtain feedback, and make improvements.
Few companies in deeply segmented industrial structures can complete this cycle in-house.
## Solution: A Self-Contained Model that Directly Integrates Customer Voices into Products and Advertising
The structure Tsugi no Tomoshibi has built with "SUSU-GOROSHI" is as follows:
Comparison Item: Traditional Manufacturing Model: Tsugi no Tomoshibi Model
Problem Discovery: Outsourced market research: Direct collection from DPF regeneration business and SNS reviews
Product Planning/Improvement: Designed by development department: Designed by in-house team based on reviews/feedback
Manufacturing: In-house factory or outsourced: Outsourced (quality control in-house)
Sales Channels: Via trading companies, agencies, mass retailers: Direct sales via Amazon, Rakuten, own EC
Advertising/Marketing: Outsourced to advertising agencies: In-house design of Amazon ad campaigns, external ads, SNS
Customer Voice Collection: Surveys, CS department: Direct reference to SNS comments, EC reviews
Product Improvement Cycle: Yearly development cycles: Continuously reflects collected feedback in products and advertising
(As of April 2026, according to company research)
The origin of this model lies in their core business: DPF cleaning and rebuilding.
Through transactions with over 5,000 maintenance garages and transport companies nationwide (as of April 2026, according to company research), Tsugi no Tomoshibi was well aware of the field issue that "the root cause of DPF clogging is soot accumulation" even before product development.
The fundamental strength of this model is that they designed the product because they understood the field, not that they understood the field to sell the product.
## Field Episode: How "Negative Reviews" Evolved the Product Twice
For achieving bestseller status, the company cites not marketing strategies, but the process of integrating customer dissatisfaction into product improvement as its biggest winning factor.
The first improvement was the development of "Kiwami 300." Previously, the company offered "Kiwami 500" for large trucks and "Kiwami 200" for small/passenger cars. However, medium-sized truck users consistently voiced dissatisfaction, saying, "It's troublesome to have to divide Kiwami 500." This feedback was directly integrated into product planning, and "Kiwami 300," perfectly suited for medium-sized trucks, was launched in June 2025.
The second improvement was the change in can shape. When "Kiwami 300" and "Kiwami 200" had the same wide can shape as "Kiwami 500," multiple reviews stated, "It's hard to pour into the fuel tank." In response to this feedback, the company updated the can to a slender shape, eliminating the inconvenience during use.
Both improvements were realized by directly referring to reviews on their own EC site and SNS comments, without involving external market research firms.
## What is an Amazon Bestseller? The Meaning of Continuously Being Chosen in a Category with Tens of Thousands of Competitors
The Amazon "Bestseller" badge, in each category is...
The company's diesel vehicle fuel additive "SUSU-GOROSHI" (Soot Killer) series ("Kiwami 500", "Kiwami 300", "Kiwami 200") achieved bestseller status in the Amazon "Automotive Diesel Additives" category on April 19, 2026. This achievement is not due to a single initiative.
It is the result of three factors working simultaneously: a development system that directly incorporates customer feedback into product improvements, an advertising strategy integrated both on and off Amazon, and a business structure that self-directs the entire value chain excluding manufacturing.
This model, distinct from the traditional Japanese manufacturing industry's reliance on division of labor and trading company distribution, illustrates a concrete vision for the role local ventures can play in decarbonizing industrial sites towards the realization of GX (Green Transformation) and Carbon Neutrality 2050.
## Societal Background: The "Common Sense of Division of Labor" in Manufacturing and its Limits
Japanese manufacturing has developed a sophisticated system of division of labor. Specialized organizations handle product planning, R&D, manufacturing, logistics, sales, and marketing, historically achieving efficiency and quality improvement in each process. However, this structure has inherent challenges from the perspective of adapting to environmental changes.
Information tends to be altered or delayed as field issues pass through multiple organizations before reaching product planning. In distribution via trading companies and agencies, end-user voices rarely reach manufacturers directly. When advertising and PR are outsourced to external agencies, communication often lacks on-the-ground knowledge.
The GX policy and circular economy promoted by the government necessitate a cycle where companies with on-site challenges design solutions themselves, deliver them directly to the market, obtain feedback, and make improvements.
Few companies in deeply segmented industrial structures can complete this cycle in-house.
## Solution: A Self-Contained Model that Directly Integrates Customer Voices into Products and Advertising
The structure Tsugi no Tomoshibi has built with "SUSU-GOROSHI" is as follows:
Comparison Item: Traditional Manufacturing Model: Tsugi no Tomoshibi Model
Problem Discovery: Outsourced market research: Direct collection from DPF regeneration business and SNS reviews
Product Planning/Improvement: Designed by development department: Designed by in-house team based on reviews/feedback
Manufacturing: In-house factory or outsourced: Outsourced (quality control in-house)
Sales Channels: Via trading companies, agencies, mass retailers: Direct sales via Amazon, Rakuten, own EC
Advertising/Marketing: Outsourced to advertising agencies: In-house design of Amazon ad campaigns, external ads, SNS
Customer Voice Collection: Surveys, CS department: Direct reference to SNS comments, EC reviews
Product Improvement Cycle: Yearly development cycles: Continuously reflects collected feedback in products and advertising
(As of April 2026, according to company research)
The origin of this model lies in their core business: DPF cleaning and rebuilding.
Through transactions with over 5,000 maintenance garages and transport companies nationwide (as of April 2026, according to company research), Tsugi no Tomoshibi was well aware of the field issue that "the root cause of DPF clogging is soot accumulation" even before product development.
The fundamental strength of this model is that they designed the product because they understood the field, not that they understood the field to sell the product.
## Field Episode: How "Negative Reviews" Evolved the Product Twice
For achieving bestseller status, the company cites not marketing strategies, but the process of integrating customer dissatisfaction into product improvement as its biggest winning factor.
The first improvement was the development of "Kiwami 300." Previously, the company offered "Kiwami 500" for large trucks and "Kiwami 200" for small/passenger cars. However, medium-sized truck users consistently voiced dissatisfaction, saying, "It's troublesome to have to divide Kiwami 500." This feedback was directly integrated into product planning, and "Kiwami 300," perfectly suited for medium-sized trucks, was launched in June 2025.
The second improvement was the change in can shape. When "Kiwami 300" and "Kiwami 200" had the same wide can shape as "Kiwami 500," multiple reviews stated, "It's hard to pour into the fuel tank." In response to this feedback, the company updated the can to a slender shape, eliminating the inconvenience during use.
Both improvements were realized by directly referring to reviews on their own EC site and SNS comments, without involving external market research firms.
## What is an Amazon Bestseller? The Meaning of Continuously Being Chosen in a Category with Tens of Thousands of Competitors
The Amazon "Bestseller" badge, in each category is...