What DIAMOND does

Diamond Inc. (株式会社ダイヤモンド社) is a privately held Japanese publishing and media conglomerate founded in 1913, headquartered in Tokyo's Jingumae district with 213 employees as of April 2026. The company operates four integrated business lines: book publishing (~130+ new titles annually across business, management, self-improvement, and fiction genres, including million-copy bestsellers such as 嫌われる勇気 at 3.3M+ copies), magazine publishing (flagship weekly 週刊ダイヤモンド repositioned to subscription-only in April 2025, monthly personal finance magazine ダイヤモンドZAi, and the exclusive Japanese edition of Harvard Business Review), digital media (Diamond Online, Zai Online, Zai FX!, Diamond Premium), and business solutions (corporate publishing, the ダイヤモンド経営者倶楽部 executive network with ~680 member companies, ドラッカー塾 Drucker management seminars, and HR assessment tools including the DPI aptitude test serving 5,000+ corporate clients).

The company's revenue model is hybrid, combining recurring subscription revenue (Diamond Weekly at 38,000 yen/1-year and 99,000 yen/3-year, Diamond Premium digital subscriptions), transactional book sales through a dedicated bookstore sales force and digital storefronts, B2B advertising on Diamond Online and affiliated media, and B2B HR solution and training content sales. Diamond's go-to-market is sales-led, with direct field sales teams targeting both consumer subscribers and enterprise clients, supplemented by its own e-commerce properties and major third-party e-book platforms (Kindle, kobo, Kinoppy, honto). All Diamond Group services are unified under the Diamond ID account system (launched March 2022), enabling cross-platform identity and engagement tracking.

The company's strategic positioning rests on its 110+ year editorial heritage, exclusive content licenses (notably Harvard Business Review), a diversified multi-platform media ecosystem, and established bookstore distribution. Recent structural moves include divestiture of the travel-guide subsidiary Diamond Big to Gakken Plus (2021), restructuring of the database service business into a separate entity (2021), subscription-model transition for Diamond Weekly (2025), digital subscription launch for Diamond ZAi (2026), and a planned CEO succession from Ishida Tetsuya to Aso Yuji effective April 2026.

Name

DIAMOND

Legal name

株式会社ダイヤモンド社

Website

https://diamond.co.jp

Company type

Private

Founded year

1913

Operating status

Operating

Headcount range

101–250 employees

Short description

Diamond Inc. (株式会社ダイヤモンド社) is a privately held Japanese publishing conglomerate founded in 1913, producing business magazines (Diamond Weekly, ZAi, DHBR), books, digital media, and HR/training solutions for individual readers, investors, executives, and corporate clients across Japan.

Ownership category

akta.pro rank

Product category

Business Media Publishing

NAICS

Newspaper, Periodical, Book, and Directory Publishers (5131), Book Publishers (51313)

SIC

Books: Publishing Or Publishing & Printing (2731)

akta.pro primary industry

Business, Finance & Industry Trade Magazines (MPAJAEAM)

Keywords

• Business media publishing
• Business magazines
• Book publishing
• HR solutions
• Financial media

Headquarters

HQ city

Akasaka

HQ country

Japan

HQ region

Asia

Offices1 record

Markets served

GTM type

B2B and B2C

Offering type

Services

Cost components

Personnel, Operations, Marketing or Sales, Supply Chain, Technology or R&D, Others

Revenue model

1. 書籍・雑誌出版事業: Publishing and sales of books (紙版・電子版) and magazines including 週刊ダイヤモンド, ダイヤモンドZAi, DIAMONDハーバード・ビジネス・レビュー, and specialized retail media titles (チェーンストア, ホームセンター, المخدرات). Revenue from retail sales, subscriptions, and digital subscriptions.
2. 雑誌定期購読・デジタルサブスク: Recurring subscription revenue from magazine subscriptions (周刊 Diamond, DHBR, ZAi) and digital subscription services such as ダイヤモンド・プレミアム and DHBR電子版, as well as the recently launched ダイヤモンドZAi digital subscription.
3. 人材開発・教育事業: HR solutions including aptitude testing (DPI), educational text materials, and corporate training programs. Revenue from B2B sales of assessment tools and training content to enterprise clients.
4. ソリューション事業: Business solutions including advertising on Diamond Online, ザイ・オンライン, ザイFX!, event sponsorship, branded content, and corporate publishing collaboration with enterprises (企業出版).
5. 雑誌・WEB広告事業: Advertising and promotion services for corporate clients using Diamond's media assets including ダイヤモンド・オンライン, ザイ・オンライン, ザイFX!, and printed magazines. Revenue from native advertising, banner ads, event sponsorship, and PR content.

Pricing tiers

Go-to-market motion1 record

Distribution channels6 records

Marketing channels7 records

Core offering

Diamond Inc. publishes business, economics, and personal-finance magazines (Diamond Weekly, Diamond ZAi, DIAMOND Harvard Business Review, and trade titles such as Diamond Chain Store, Diamond Home Center, and Diamond Drug Store), sells books across business, self-help, children's, and fiction categories, and operates digital media platforms (Diamond Online, Zai Online, ZaiFX!). Beyond content, the company provides B2B HR solutions (DPI aptitude testing, training content), corporate publishing services, executive networking (Diamond Executives Club, Drucker-juku seminars), advertising solutions across its media properties, and digital archive subscriptions of historical magazine issues.

Product overview

DIAMOND is a Japanese publishing conglomerate with a portfolio of print, digital, and services businesses. Its core publishing products include the weekly business magazine Diamond WEEKLY (shifted to subscription-only from April 2025), the monthly personal finance magazine ダイヤモンドZAi, and the licensed DIAMONDハーバード・ビジネス・レビュー (Japanese edition of Harvard Business Review), alongside specialized trade magazines ダイヤモンド・チェーンストア, ダイヤモンド・ホームセンター, and ダイヤモンド・ドラッグーストア under the ダイヤモンド・リテイルメディア brand. Its digital platforms include ダイヤモンド・オンライン (business news), ザイ・オンライン (personal finance), ザイFX! (forex), and the paid subscription service ダイヤモンド・プレミアム, all unified under the ダイヤモンドID account system. The book publishing division publishes approximately 130+ titles annually across business, management, self-improvement, children's books, and fiction — notable for million-copy sellers including the 嫌われる勇気 series (3.3M copies) and the もし高校野球 series (2.75M copies). Business solutions include enterprise publishing, the ダイヤモンド経営者俱楽ubo membership network (~680 companies), ドラッカー塾 management seminars, DPI-based HR assessment tools and training content (~5,000+ client companies), digital archives of 100+ years of Diamond Weekly, and targeted magazine distribution services.

Differentiator

Problem solved

Functional benefit

Brands

• ダイヤモンド・オンライン (Diamond Online): Japanese business media targeting executives and decision-makers, with articles on macroeconomics, business management, careers and professional development.
• ダイヤモンドZAi
• DIAMONDハーバード・ビジネス・レビュー (DHBR)
• Diamond WEEKLY (週刊ダイヤモンド)
• ザイ・オンライン
• ザイFX!
• ダイヤモンド不動産研究所
• DIAMOND Quarterly
• ダイヤモンド教育ラボ
• HRオンライン
• ダイヤモンド・チェーンストア
• ダイヤモンド・ホームセンター
• ダイヤモンド・ドラッグ
• ダイヤモンド・ビッグ社

Products and services

• Diamond WEEKLY A weekly business magazine founded in 1913 as the company's flagship publication. As of April 2025, it was repositioned as a subscription-only magazine targeting business professionals with in-depth economic, industrial, and corporate coverage delivered across print and digital formats, priced at 1,320 yen per issue.
• Diamond ZAi (ダイヤモンドZAi) Japan's top-circulation monthly personal finance/investment magazine, covering stocks, investment trusts, NISA, tax planning, and retirement planning for individual investors. Published monthly on the 21st, priced at 850 yen per issue.
• DIAMOND Harvard Business Review (DHBR) An exclusive Japanese-language licensed edition of Harvard Business Review, published monthly under agreement with Harvard Business School Publishing. Targets business leaders and managers with first-run academic and practical management articles, book reviews, and case studies, priced at 2,300 yen per issue.
• Diamond Chain Store (ダイヤモンド・チェーンストア) A semimonthly (1st and 15th) trade magazine for retail/distribution industry professionals covering retail strategy, supply chain, and store management. Priced at 1,650 yen per issue.
• Diamond Home Center (ダイヤモンド・ホームセンター) A bimonthly specialized trade magazine exclusively covering the home center/DIY industry. Priced at 3,150 yen per issue.
• Diamond Drug Store (ダイヤモンド・ドラッグ) A bimonthly specialized trade magazine for the drugstore and cosmetics retail industry. Priced at 1,650 yen per issue.
• Diamond MOOK M&A Annual (ダイヤモンドMOOK M&A年鑑) An annual special edition (MOOK) dedicated to mergers and acquisitions trends, deal league tables, and M&A strategy. Priced at 1,980 yen.
• Diamond Online (ダイヤモンド・オンライン) A major Japanese business digital media platform targeting executives and decision-makers. Offers original investigative reporting, expert columns, and video content across macroeconomics, corporate management, international affairs, careers, and workplace topics.
• Zai Online (ザイ・オンライン) A digital personal finance and investment media platform covering global stocks, forex, and financial markets with analyst columns, investment articles, financial product comparison tools, and financial life-hack content.
• ZaiFX! (ザイFX!) A specialized digital platform for forex (FX) trading information, offering market analysis, trading strategy content, and forex-related news for retail investors.
• Diamond Premium (ダイヤモンド・プレミアム) A paid digital subscription service offering exclusive premium content including in-depth analysis, special reports, and subscriber-only articles from the Diamond Weekly editorial team. Offered as a standalone subscription and bundled with the print magazine (annual set 36 issues at 47,300 yen; 3-year set 108 issues at 128,700 yen).
• Book Publishing (書籍出版事業) Diamond's book publishing division produces business books, management, self-improvement, children's books, novels, and practical/lifestyle titles, publishing approximately 130+ new titles annually. Notable for million-copy sellers including the 'The Courage to Be Disliked' series (3.3M+ copies) and the 'If High School Baseball Team Managers Read "Management"' series (2.75M copies).
• Corporate Publishing Service (企業出版サービス) A collaborative publishing service for companies seeking strategic book publication as a corporate communications tool. Diamond provides editorial, design, and distribution support for corporate-authored books.
• Diamond Executives Club (ダイヤモンド経営者倶楽部) A membership-based networking organization for business owners and executives. As of September 2024, approximately 680 member companies participate, representing mid-tier, small, and owner-operated businesses across Japan.
• Drucker-juku (ドラッカー塾) A management training seminar program based on Peter Drucker's management theory, offering structured learning and practice of fundamental management principles for executives, managers, and aspiring business leaders.
• DPI HR Solutions (適性検査・社内教育ツール) HR solutions including the DPI (Workplace Adaptability Test), aptitude tests, new employee training tools, business skill textbooks, and talent development/assessment programs. The company claims 5,000+ client companies. Services include assessment tools, onboarding content, and training programs developed through industry-academia collaboration.
• Weekly Diamond Digital Archives (週刊ダイヤモンド デジタルアーカイブズ) A library-oriented digital archive service providing scanned images of all Diamond Weekly magazine issues from the founding issue (1913) through year 2000 — approximately 4,000 issues and 250,000 pages — for institutional access.
• Target Magazine (ターゲットマガジン) A targeted magazine subscription distribution service enabling companies to reach specific audience segments through curated magazine subscription bundles as part of corporate PR and marketing campaigns.
• Diamond Executive Card (ダイヤモンド・エグゼクティブカード) An executive membership/premium service offering exclusive content, privileges, and networking opportunities for high-level business executives, with a dedicated portal and premium brand communications.
• Zai Investment Trust Awards (ザイ・オンライン 投信グランプリ) An annual investment trust award program organized by Diamond ZAi magazine, recognizing top-performing NISA-eligible active funds across categories including Japanese equity, global equity, REIT, and others. The 2025 edition (3rd annual) featured 11 consecutive awardees including 5 triple-consecutive winners.

Quantifiable outcome

• 5 million-copy bestsellers including '嫌われる勇気' (3.3M+ copies) and 'もし高校野球の女子マネージャーが...' (2.75M+ copies)
• +2 more outcomes

Named customers4 records

Segments4 records

Ideal customer profiles5 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Partnerships

Five partnerships are on record, tiered minor and major.

• 株式会社ダイヤモンド企業情報編集社minorStrategic or Co-development Partner · 2 August 2021Diamond Inc. transferred its enterprise information editorial business to a dedicated company, 株式会社ダイヤモンド企業情報編集社, to further develop its database service offerings. The ダイヤモンドデータベースサービス continues under the new entity.
• 株式会社学研プラス（株式会社学研ホールディングス）majorStrategic or Co-development Partner · 16 November 2020Diamond Inc.'s subsidiary, 株式会社ダイヤモンド・ビッグ社 (established 1969), transferred its publishing business centered on the 地球の歩き方 (Arubeni no Arukikata) travel guide series to 学研プラス. The transfer was completed January 1, 2021, in response to significant changes in the overseas travel industry environment caused by the COVID-19 pandemic.
• Harvard Business School Publishing CorporationmajorStrategic or Co-development PartnerLong-standing exclusive licensing partnership for the Japanese edition of Harvard Business Review. Diamond Inc. publishes DIAMONDハーバード・ビジネス・レビュー (DHBR) under this license, providing Japanese readers access to world-class management research and case studies from Harvard Business School faculty and global business leaders.
• 株式会社ダイヤモンド・フィナンシャル・リサーチminorStrategic or Co-development PartnerDiamond Group company with which Diamond Inc. jointly uses personal customer data for email newsletter and information distribution services. Listed as a joint use partner under Japan's Personal Information Protection Act.
• 株式会社識学（安藤広大）minorStrategic or Co-development PartnerDiamond Inc. published the '数値化の鬼' (173万部突破 as of July 2025) and related four-book series by Ando Kodai, CEO of 識学. The series represents a flagship author partnership that generated significant revenue and brand value for Diamond's business book publishing.

Scale indicators6 records

Recent moves8 records

Expansion highlights5 records

Others

• Magazine House (マガジンハウス): Specialized Japanese consumer magazine publisher (anan, BRUTUS, POPEYE, etc.); relevant peer for Diamond's print magazine operations even though its verticals are lifestyle rather than business/trade.
• Hakuhodo (博報堂): Major Japanese advertising and integrated marketing solutions firm; competes for the same corporate advertising budgets and B2B media solutions revenue that Diamond Online monetizes.
• PHP Institute (PHP研究所): Business and self-improvement book publisher with topic overlap to Diamond's business/self-help list; competes for similar business-book authors and buyer demographics in Japan.
• Benesse Holdings: Education, publishing, and HR/learning services holding company; comparable on the HR solutions and education/training content axes that Diamond's B2B solutions business serves.

Broad incumbents

• Kodansha (講談社): One of Japan's largest general-interest trade book publishers and a major magazine publisher; comparable on book publishing scale and magazine diversity even though its content mix leans more consumer.
• Shueisha (集英社): Major Japanese publisher spanning books, manga, and magazines; a relevant scaled publishing comparable even though its strengths (manga/light content) differ from Diamond's business focus.
• KADOKAWA (KADOKAWA Corporation): Large Japanese publishing and media conglomerate spanning book publishing, periodicals, digital, and education; a scaled multi-segment publishing peer comparable to Diamond's diversified model.
• Recruit Holdings: Diversified Japanese media and HR solutions conglomerate; overlaps directly with Diamond's HR Solutions business (assessment, training, recruitment media) and shares the same enterprise talent-management customer base.

Direct peers

• Toyo Keizai Inc. (東洋経済新報社): Publisher of the long-running weekly business magazine 東洋経済 and a strong business book imprint; the closest comp to Diamond Weekly + Diamond ZAi + business book publishing under one roof in Japan.
• Nikkei BP (日経BP): Japan's leading business-to-business magazine and digital media publisher (Nikkei Business, Nikkei TRENDY, etc.); competes head-on with Diamond for business readership, executive advertising, and corporate content services.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks6 records

Key highlights6 records

Customer concentration

• Xtwitter.com/diamond_sns

Revenue estimate

Valuation estimate

Number of profiles

Profiles9 records

Subsidiaries1 record

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about DIAMOND