---
license: cc-by-4.0
language:
- en
- ja
tags:
- construction
- cost-estimation
- fraud-detection
- consumer-protection
- japan
- residential-renovation
- llm
- nlp
size_categories:
- n<1K
pretty_name: Japan Construction Cost Database
---

# Japan Construction Cost Database (JCCDB)

An openly licensed structured dataset linking residential construction plan-level pricing, contractor-size-tier margin ranges, and fraud-detection patterns for the Japanese market.

## Overview

JCCDB is the first openly licensed dataset of its kind for Japan's ¥7.35-trillion-per-year residential renovation market. It comprises:

- **87 construction plans** across 7 renovation categories (roof, termite control, water heater, window, bathroom, kitchen, electrical)
- **88 fraud-detection patterns** annotated by severity
- **4-tier contractor-size margin ranges** (sole proprietor → mid-size → major → national chain)
- Pricing grounded in 2026 Kanto-region trade-price data and 30 years of construction management experience
- Quarterly recalibration via Bank of Japan CGPI integration

## Use Cases

- Training and evaluating LLM-based cost estimation systems
- Consumer-protection research and fraud detection benchmarks
- Cross-country comparative construction-economics analysis
- Real-world LLM application case studies in non-English markets

## Citation

```bibtex
@misc{oga2026jccdb,
  title  = {Japan Construction Cost Database: An Open Dataset for LLM-Based Cost Estimation and Fraud Detection in Residential Renovation},
  author = {Oga, Toshikatsu},
  year   = {2026},
  doi    = {10.31224/7007},
  url    = {https://engrxiv.org/preprint/view/7007}
}
```

## Links

- **Paper (engrXiv):** https://doi.org/10.31224/7007
- **Original dataset (Zenodo):** https://doi.org/10.5281/zenodo.20019573
- **Code (GitHub):** https://github.com/ogasurfproject-jpg/japan-construction-cost-database
- **Author ORCID:** 0009-0000-9180-903X
- **Service (HORIZON SHIELD):** https://shield.the-horizons-innovation.com

## License

Creative Commons Attribution 4.0 International (CC-BY 4.0). Free for commercial and non-commercial use with attribution.

## Author

Toshikatsu Oga — The HORIZ音s Co., Ltd. (Japan)
30 years in residential construction (carpenter → site supervisor → CM → AI engineer)