盾
Show HN · May 2026
Toshikatsu Oga · The HORIZONs Inc.
Tamper-proof AI
for construction
quotes.
A 30-year carpenter built the system
contractors couldn't game.
shield.the-horizons-innovation.com · @toshikatsu-oga
The Problem
Japan's hidden
¥1.1T fraud layer.
¥7.35T
Annual renovation market
15–20%
Systemic overcharging rate
200–300%
Hidden markups in lump sums
一式
"Lump sum" — the contractor's shield.
A single line item can hide ¥500,000 in undisclosed markups. 30 years on job sites. Thousands of families overcharged. No tool existed to verify.
The Founder
Carpenter.
Then engineer.
1994
First nail. First site.15 years old. Apprenticed as a carpenter in Shimane Prefecture.
2024
First line of code. Age 47.ChatGPT arrived. Homeowners started asking it for second opinions — and got different numbers every time.
2026
HORIZON SHIELD ships.30 years of field knowledge, encoded. Deterministic. Tamper-proof.
"Framing a house at 16 was harder than learning to code at 47."
The Architecture
Deterministic
by design.
Input
LLM Layer
Natural language
parsing only.
No arithmetic.
→
Core
JCCDB v1.2.1
3,350+ items.
4 contractor tiers.
Real-time WPC.
→
Output
SHA-256 Report
12-char audit hash.
Same input →
same answer.
Same input → same hash → same answer
EU AI Act Art. 12/14 aligned
Human oversight built in
Technology
Six layers.
Zero ambiguity.
⬡
Deterministic Core
LLM handles only language. Numbers come from a versioned database, not a prediction.
#
SHA-256 Audit
Every report carries a 12-char hash of canonical input + DB version. Immutable audit trail.
▲
War Price Coefficient
Real-time supply-chain adjustment. Tracks global material volatility. Updated monthly.
≡
4-Tier Pricing
Sole trader → Major firm. 25–45% margin ranges. Contractors can't hide inside a tier.
⬡
Cloudflare Edge
Workers + KV + R2. Zero cold start. Global. 16 API endpoints. PDF generation on-demand.
◎
Open Dataset
JCCDB v1.1 — CC-BY 4.0. 3,350 items. Peer-reviewed via engrXiv DOI 10.31224/7007.
×1.0935
War Price Coefficient
Live · +9.35% supply-chain premium
Traction
Built in public.
Validated by press.
79
Media Outlets
PR TIMES distribution · organic pickup
3,350
DB Line Items
JCCDB v1.2.1 · 7 categories · CC-BY 4.0
1
Peer-Reviewed Paper
engrXiv DOI 10.31224/7007 · SSRN 6738701
¥0
Paid Acquisition
100% organic · built in 8 weeks
Market
Japan first.
Global next.
¥7.35T
Japan residential renovation
$11.4T
Global construction market
$1.8T
Addressable overcharge problem
Now
Japan B2C
¥5,500–¥88,000
2026 Q4
API licensing
for insurers / banks
2027
SE Asia
construction markets
2028
KURO-AN
$50K/unit US export
Contact
Let's build
the honest
layer.
◎
Live Service
shield.the-horizons-innovation.com/index_en.html
#
Open Dataset — JCCDB v1.1 CC-BY 4.0
github.com/ogasurfproject-jpg/japan-construction-cost-database
▲
Research Paper — engrXiv
DOI 10.31224/7007 · SSRN 6738701 · ORCID 0009-0000-9180-903X
"The dataset and the commercial service are intentionally separated —
research data is CC-BY 4.0 forever, the API pays rent."