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About Me.

I am a freelance software engineer based in Hokkaido, Japan.

My work primarily focuses on business application development, along with cloud architecture, infrastructure engineering, automation, and AI-powered solutions.

I enjoy exploring new technologies and continuously expanding my knowledge across a wide range of technical fields.

From technology selection and architecture design to modernizing existing systems, I strive to understand the challenges behind each project and deliver practical solutions that best fit its needs.

Thank you for visiting my portfolio. I look forward to the opportunity to work with you.

About

  • Freelance Since March 2020
  • Experience 20+ Years
  • Focus Areas System Development / Cloud / AI
  • Main Stack C#/.NET, Python, Go
  • Location Japan (Hokkaido)
  • Work Style Remote & On-site
  • Timezone JST (UTC+9)
  • Languages Japanese / English

Skills

Languages & Backend
C# / .NET Python SQL Go C / C++ Rust PHP Visual Basic
Web & Frontend
JavaScript / TypeScript HTML / CSS React Next.js Vite Tailwind CSS ASP.NET jQuery
Cloud & Infrastructure
AWS Azure GCP OCI Cloudflare Docker CloudFormation Terraform Microsoft Entra ID Linux
Scripting & Automation
Bash / Shell PowerShell GitHub Actions GitLab CI Jenkins
AI & Machine Learning
PyTorch TensorFlow OpenCV LLM API
Security & Testing
Burp Suite Kali Linux k6 Vulnerability Assessment
Databases
PostgreSQL SQL Server Oracle MySQL / MariaDB MongoDB SQLite Redis
OS
Windows Debian / Ubuntu RHEL / AlmaLinux Amazon Linux macOS / iOS FreeBSD
Tools
Git / GitHub / GitLab WSL VS Code / Visual Studio JetBrains IDEs Jira / Confluence draw.io Claude / ChatGPT / GitHub Copilot

Key Projects.

Software Engineer

Administrative Agency Maintenance Management System

Migrated an existing VB.NET-based desktop system to a web application, integrating GIS (Geographic Information System) functionality along the way. Led the project from requirements definition and system design to cloud environment setup and implementation.

Impact Selected a next-generation platform balancing requirements and budget. GIS integration improved operational efficiency.
VB.NET ASP.NET MongoDB GCP Google Maps API

Software Engineer

GitHub Issue / PR Auto-Check App

Built a GitHub App that detects new issues and pull requests via webhooks, automatically checking their content, applying labels, and assigning reviewers.

Impact Reduced manual work before review and eliminated missed checks.
Go GitHub GitHub Apps Webhook

Cloud Engineer

Government System Integration & Cloud Migration

Integrated multiple legacy systems into a new centralized platform and migrated them to the public cloud. Built and maintained infrastructure with CloudFormation, centralized authentication via Microsoft Entra ID, and mentored team members new to the cloud.

Impact Reduced operational costs and improved management efficiency. Introduced AI-powered tools to automate QA handling.
AWS Azure Microsoft 365 Slack CloudFormation Terraform

Machine Learning Engineer / Data Scientist

Image Analysis AI for Infrastructure Inspection

Developed an AI-based system for government agencies that detects cracks and other defects in infrastructure from images. Responsible for model design, training data preparation, accuracy improvement, and API development.

Impact Delivered higher accuracy than third-party vendor proposals, leading to adoption. API integration connected the AI service with business systems.
Python PyTorch OpenCV ASP.NET GCP

Backend Engineer

Slack-Operated AWS Automation App

Developed an app in which an LLM interprets Slack messages and executes operations on AWS resources.

Impact Enabled day-to-day AWS operations to be completed entirely from Slack, without the AWS console.
Python Slack AWS LLM API

QA Engineer / Security Testing

API Load Testing & Vulnerability Assessment

Designed and ran API load tests and verified authentication flows. Discovered an authorization flaw that allowed impersonating a user other than the one logged in.

Impact Detected and reported a critical authorization flaw before release, leading to a fix.
AWS k6 Burp Suite