Software Engineer with extensive experience in full-cycle
development, ranging from robust development of payment and banking
systems with Ruby and Go to SPA/MPA development using React. My
strengths lie in software design within System of Record domains and
implementing solutions with a focus on performance and scalability. I
actively contribute to the engineering community through OSS projects
and technical presentations. For additional information, please see Public Output.
I have also served as an Engineering Manager in organizations of
20-60 engineers, gaining substantial experience and expertise in team
design, project management, recruitment, corporate branding, culture
building, and community activities.
My core strength is the ability to foster team technical growth while
ensuring quality and robustness in mission-critical development, from
batch processing idempotency to data consistency in payment systems.
Skills
Programming Languages: Ruby, TypeScript, Go
Frameworks & Libraries: Ruby on Rails, React,
React Admin
Cloud Infrastructure & DevOps: AWS, GitHub
Actions, CircleCI, New Relic, Google BigQuery
Soft Skills: Team Collaboration, Agile
Methodologies, Engineering Management, Scrum
Professional Experience
The following achievements are further detailed through my technical
presentations and blog posts. For additional information, please see the
Presentations and Blogs sections below.
SmartBank, Inc.
Period
Role
Aug 2020 - Present
Senior Software Engineer
Oct 2023 - Present
Engineering Manager
SmartBank, Inc. is a BtoC
Fintech company that is categorized as a challenger bank
like Monzo. The company is an “Issuer”
that issues prepaid cards and develops and operates a product named B/43 that visualizes and automates spending
management in conjunction with payment with cards.
Achievements:
Subscription Service Development (Oct 2022 -) :
Developed subscription service from scratch without using any external
SaaS.
(Dec 2023 - Oct 2024) Increased subscription revenue by launching an
aggregation service that fetches spending data from other financial
institutes.
Banking System Development (Aug 2020 -) : Developed
various features like withdrawal, money transfer, account by purpose,
joint account, pending management and etc.
(Nov 2021 - Jun 2022) Developed 3-D Secure authentication for secure
card payments.
(Aug 2020 - Apr 2021) Developed an in-house identity verification
system (known as eKYC) / Card delivery system that performs necessary
works as a card issuer.
Developer Experience Improvements (Aug 2020 -) :
Developed tools and systems for internal developers.
Introduced Feature
Toggles and separated development and release.
Made our API server compatible with Idempotency-Key
Headers and make it robust so that data can be protected even if
multiple requests occur.
Contributed to development productivity. e.g. Built CI/CD pipeline,
automated deployment flow, schema/date migration flow, and migrated
queueing system from Delayed Job to SQS.
Quipper Limited
Period
Role
Aug 2015 - May 2020
Senior Software Engineer
Jun 2017 - May 2020
Engineering Manager
Quipper is a company that
operates both B to C and B to B education businesses. We develop and
operate Quipper School and Quipper Video outside of Japan, and StudySuppli in Japan.
Achievements:
Large-scale Code Cleanup (Mar 2020) : Led removal
of 400,000 lines of code with zero production incidents, improved
maintainability by reducing Rails models from 390 to 281.
React Native to PWA Migration (Jul - Sep 2019) :
Led platform migration of internal business application.
Payment System Improvements : Implemented
auto-renewable subscription feature for iOS app, and A/B tested payment
method optimization.
Junior High School Coaching Service Development
(Aug 2018 - Mar 2019) : Led 12-member team to successful launch of
high-uncertainty project, enhancing team productivity through mob
programming and 1-on-1s
Entry Form Modernization (Mar 2018) : Improved
registration CVR through modernization of legacy system.
Recruitment & Organization Design (Jul 2016 -
Mar 2020) : Led recruitment efforts, designed structured interviews, and
improved onboarding process.
SCSK is a Japanese big information
technology services company. I was a member of a department developing
some enterprise systems for real estate companies which needs better
property management solutions. I’ve developed web applications for the
purpose.
Public Output
OSS Activities
Pull
requests list. I have also sent patches to major OSS such as
Node.js, yarn, Ruby, etc.
The purpose of this community is to share knowledge about
engineering management, which is still not widely available in Japan. In
total, more than 500 people participated in the event. I’ve been running
it on my own for about 1.5 years. In 2020, I’ve handed over the
community management to the community.