Japanese AI Company Makes Major Expansion of Open Construction Cost Database — SSRN-Verified, Bitcoin-Anchored

HORIZON SHIELD releases JCCDB v2.0 item schema (65,729 items / 398 categories) on GitHub under CC BY-NC 4.0; companion diagnostic paper approved by SSRN (Elsevier) on May 18, 2026

HIRATSUKA, JAPAN — The Horizons Co., Ltd. today publicly released the item schema of its Japan Construction Cost Database v2.0 (JCCDB v2.0) — a comprehensive open schema containing 65,729 items across 398 categories covering all 28 standard Japanese construction trades.

Originally developed as the internal pricing engine for the HORIZON SHIELD AI diagnostic service, the schema is now made available to the public under CC BY-NC 4.0 (non-commercial use with attribution). Full price data remains proprietary for the commercial diagnostic service.

The companion academic paper detailing the diagnostic methodology was approved by SSRN (Social Science Research Network, Elsevier) on May 18, 2026.

SSRN Approval & Cryptographic Verification

• SSRN Paper: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=6738701
• DOI (engrXiv): 10.31224/7007
• DOI (Zenodo): 10.5281/zenodo.20019573
• Bitcoin Permanent Anchor: Block #949356 (May 14, 2026 JST)
• PTKA Declaration SHA-256: 596da30ba4ca731f21efaa1c4a6537290e996e0f039cbe57704de1674e4a0282
• Each diagnosis case includes a 12-character cryptographic audit hash for independent verification

Key Findings from 20 Real Diagnosis Cases

• Average overcharge: ¥825,000 (~$5,775 USD)
• Maximum overcharge: ¥2,800,000 (~$19,600 USD) — 84.9% markup
• Maximum fraud rate case: termite extermination, Chiba Prefecture (quoted ¥1,850,000; fair price ¥280,000)
• 15 prefectures / 20 construction categories covered

“A diagnostic methodology that cannot be independently verified loses credibility. By anchoring our core methodology to the Bitcoin blockchain and receiving SSRN academic approval, we created a reference that contractors, homeowners, and regulators can all trust.”

— Toshikatsu Oga, Representative Director, The Horizons Co., Ltd.

Founder Background

Toshikatsu Oga, a former carpenter with 30 years of hands-on experience, transitioned to self-taught AI engineering and built HORIZON SHIELD to reduce information asymmetry in Japan’s renovation market. He began a carpentry apprenticeship at age 15 in Osaka in 1993 and accumulated experience across carpentry, site supervision, and construction management before developing the JCCDB.

Availability

• Service: https://shield.the-horizons-innovation.com
• JCCDB v2.0 Schema (CC BY-NC 4.0): https://github.com/ogasurfproject-jpg/japan-construction-cost-database
• SSRN Paper (CC-BY 4.0): https://papers.ssrn.com/sol3/papers.cfm?abstract_id=6738701
• 20-Case Diagnosis Dataset (CC-BY 4.0): https://shield.the-horizons-innovation.com/jireishuu_en.html
• Bitcoin Verification: Block #949356 via OpenTimestamps (https://opentimestamps.org)

About The Horizons Co., Ltd.

Headquartered in Hiratsuka, Kanagawa, Japan, The Horizons Co., Ltd. (The HORIZ音s株式会社) develops AI solutions for fairer construction pricing.

Media Contact

Toshikatsu Oga, Founder & Representative Director

Email: contact@the-horizons-innovation.com

Team: teamhorizonshield@gmail.com

Web: https://shield.the-horizons-innovation.com

ORCID: 0009-0000-9180-903X

JCCDB v2.0 Schema (CC BY-NC 4.0) | JCCDB v1.2.2 Paper (CC-BY 4.0) | SSRN Approved 2026-05-18 | Bitcoin Block #949356