Yuya Sumie

ABOUT

Yuya Sumie | 住江 祐哉

CAREER

• 2025/6 ~ NOW

  bamboooo Inc.

  CTO I co-founded the company with a friend, and we run a contract development business. I handle both the frontend and the backend, focusing on web and AI application development.

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  For a kimono remake simulation tool, I processed uploaded photos and compressed them before sending, reducing data transfer so that processing could stay within the project's constraints. For an automated quoting system driven by AI analysis of CAD drawings, I built an application that parses drawings with AI-OCR and generates quotes tailored to each client.
• 2026/7 ~ NOW

  SMART GOLF Inc.

  System development Developing systems for SMART GOLF, a 24/7 members-only indoor golf facility

• 2022/4 ~ 2026/6

  Sansan, Inc.

  Joined as a new graduate After joining, I worked on the seminar management system Seminar One, handling load countermeasures for spike traffic. I then moved to the sales DX service Sansan, where I developed features and operated/maintained one of Japan's leading SaaS applications

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  Seminar One hosts seminar registration pages, and whenever a page went public, traffic spikes caused load-related errors. I ran load tests with k6 and tuned both the application and the infrastructure. I switched database reads and writes to use I/O completion ports for better efficiency in a multithreaded environment, separated the static and dynamic parts of each page so the static parts could be cached and served through a CDN to reduce load on the origin, and adjusted the autoscaling parameters to cut the number of errors during application startup. Sansan is a SaaS that has been running for over 19 years, and its core data, business-card records, numbers in the hundreds of millions, so improving existing features and building new ones both require performance-aware development. I wrote SQL with the behavior of the PostgreSQL optimizer in mind and tuned queries with pg_hint_plan, prioritizing performance from the data-structure design stage. I also worked on a microservice architecture built on a messaging system and was involved in migrating the cloud environment from Azure/C# to GCP/Go.
• 2020/8 ~ 2022/3

  Money Forward, Inc.

  Long-term intern at the Kyoto development office Worked on performance improvements, mainly in Go, in KTA (Kyoto Development Division Technical Architect Group)

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  I worked on reducing the operating costs of Money Forward Cloud Accounting Plus. I implemented a pipeline architecture that periodically syncs binary data, previously stored in the database, to S3, cutting storage costs. I also built a dashboard to visualize development productivity and support analysis.
• 2019/10 ~ 2022/3

  HACARUS Inc.

  Long-term intern Built demo web apps for machine-learning products and set up CI for various projects

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  I developed machine-learning applications based on sparse modeling that take advantage of the structure of image and video data, including anomaly detection for continuous data such as ECGs and an annotation application for medical data. I also frequently handled CI/CD, mainly AWS permission management and deployment pipelines.
• 2021/4 ~ 2022/2

  Crosshare Inc.

  Contract development Worked as a backend engineer on a new service bringing a fresh experience to friend matching in online games

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  I built a player-matching service using Amazon GameLift FlexMatch. It matches players in real time based on their rank and play style and automatically creates a Discord chat room. I focused on concurrency control and performance.
• 2020/9

  teamLab Inc.

  Working internship Developed new features for an internal shared platform built on Spree, a Rails e-commerce framework

• 2020/9

  Howtelevision, Inc.

  Summer internship Joined a program developing new features for the company's services as a backend engineer using Go

• 2020/9

  Sansan, Inc.

  1-day internship Joined a program to experience developing a business-card management app

• 2020/8

  BrainPad Inc.

  Summer internship Built a demo app in one week to showcase Conomi, the company's in-house matching engine

• 2020/8

  Cookpad Inc.

  Online Summer Internship 2020 Joined a program covering service development from ideation to implementation, and built a service to make cooking more fun for people living alone

• 2020/4

  Cookpad Inc.

  Spring internship Joined a performance-tuning program using Ruby on Rails

• 2019/9

  OPTiM Corporation

  Short-term internship Researched accuracy improvements for an internal project using semantic segmentation

• 2019/9

  Nikkei Inc.

  HACK THE NIKKEI Processed article data and browsing history from the Nikkei digital edition, then proposed and implemented a new service for the web edition

LINKS

@MONAKA0721

@monaka_0721

@yuyasumie

@monaka0721

https://bamboooo.net

WORKS

POSTS