Overview
iOS lead engineer with 10+ years in software development, specializing in video streaming and ad monetization. I currently lead iOS development at TVer, one of Japan's largest free ad-supported streaming services, where I work on video playback infrastructure with The Composable Architecture and on the ad integration around it.
Before TVer, I led the in-housing of Voicy's iOS app — an audio streaming platform — introducing a multi-module architecture with 80%+ test coverage on new modules and reducing post-release bug reports by roughly 40%.
I also build for Android and Go on the backend, which lets me design features end to end rather than stopping at the app boundary.
Outside of work I speak at iOSDC Japan and help organize Swift愛好会 (Swift Lovers), a Japanese Swift community of 2,200+ engineers.
Background
- Full-stack background from my SIer years — infrastructure, backend and frontend
- Ships production apps on both iOS and Android, not just one platform
- Introduces and runs agile practices to move teams and projects forward
- Comfortable with stakeholder alignment and prioritization as a team lead
What I do best
- Video playback and ad monetization on mobile — player architecture, live and VOD
- Audio and live streaming infrastructure
- Product-minded engineering — deciding what to build from a business perspective, not only a technical one
Talks
iOSDC Japan 2020
“Becoming an iOS OSS contributor through the DroidKaigi official app”
Vue.js Architecting Meetup
“Understanding Vue / Vuex architecture, completely”
Community
Swift愛好会 (Swift Lovers)
connpass →Organizer of a Japanese Swift community with 2,200+ engineers, running meetups once or twice a month (98 editions and counting).
DroidKaigi
Website →Staff member of DroidKaigi, the largest Android developer conference in Japan.
Experience
TVer
Jan 2025 - Present
Project overview
iOS lead engineer at TVer, one of Japan's largest free ad-supported streaming services, working on the video playback experience and the ad integration around it.
Highlights
Video playback and ad monetization
- Work on player features for both live and on-demand streaming, including the ad integration layer around playback
- Replaced playback-related code with The Composable Architecture, improving maintainability and testability
Large-scale live event delivery
- Delivered the streaming experience for the Milano Cortina 2026 Winter Olympics, including a dedicated top screen and event UI
- Built reusable player modules covering both live and VOD playback under a hard, externally fixed deadline
CI with Xcode Cloud
- Tests existed but there was no CI. Introduced Xcode Cloud so every pull request runs automated tests and build verification
- Stabilized the development cycle for the whole iOS team
Onboarding redesign
- Rebuilt the walkthrough flow so new users understand the app immediately
Tech stack
Voicy
Dec 2021 - Dec 2024
Project overview
iOS engineer and team lead at Voicy, an audio streaming platform. As the owner of the recording app for creators, I led the move from outsourced development to an in-house team, the architecture overhaul, and new feature development.
Highlights
In-housing development and rebuilding code quality
- The app had been outsourced since the company's founding, had no unit tests, and relied on manual QA to catch bugs
- Introduced a multi-module architecture and reached 80%+ test coverage on new modules
- Drove incremental refactoring with four iOS/Android engineers without pausing feature work, cutting post-release bug reports by about 40%
Collaborative recording
- Designed and built a feature that lets creators record together remotely
- Introduced agile practices, reviewing increments weekly with the PdM and running mid-development validation with five creators
- 100+ creators adopted collaborative recording after launch
Live broadcasting
- Implemented real-time audio broadcasting on both iOS and Android using Agora
- Built the creation, start and scheduling screens from scratch, including pre-broadcast checks for network state and permissions
- Enabled low-latency delivery and listener participation for two-way communication
Backend (Go) API development
- Designed and implemented the session API for collaborative recording with OpenAPI
- Built the live broadcasting database and its APIs around Agora
- Developed the APIs for room admission, rejection and exit flows
Android work
- Designed and implemented creator-only comment display and control, including broadcast-type detection
- Migrated the Android recording app's UI components to Material 3
Hiring
- Ran first-round engineering interviews, assessing both technical skill and culture fit
- Contributed to three hires that strengthened the team
Tech stack
CBCloud
Apr 2019 - Nov 2021
Project overview
Worked on PickGo, a delivery matching platform, and SmaRyuTruck, a SaaS for freight carriers. Moved from mobile engineer to team lead, contributing on both development and customer-facing work.
Highlights
Team lead on the SmaRyuTruck launch
- Volunteered to take over as team lead partway through the project
- Coordinated development priorities and bridged stakeholders while the CEO acted as product owner
- Visited customers directly to understand real logistics operations and fed those findings into product requirements
- Built the freight delivery request page
Rebuilding the PickGo team
- After a wave of departures I was the only remaining developer on the product
- Got up to speed on the existing codebase and business flows quickly enough to keep shipping
- Delivered the JAL air freight integration alone, from requirements to release
- Implemented dynamic delivery pricing that responds to seasonal demand
Hiring
- Ran first-round engineering interviews
Deliverables
- SmaRyuTruck - SaaS for freight carriers
- PickGo - Delivery matching platform
- Shopping proxy service
Tech stack
Lifesports
Feb 2018 - Mar 2019
Project overview
Mobile app development for a sports matching service, focused on feature improvements for user growth and a new community feature.
Highlights
- Improved existing features and UI/UX to grow the user base
- Designed and implemented a community feature connecting sports enthusiasts
Tech stack
AP Communications
Sep 2013 - Feb 2018
Project overview
Started my career at a network-focused SIer, covering everything from infrastructure to application development after moving to the development division.
Highlights
- Operated and maintained a network authentication system for a major Japanese enterprise
- Joined a large-scale system replacement project, handling infrastructure setup through migration
- After moving to the development division, maintained and replaced systems for education and entertainment businesses
Tech stack
Side Projects
ishin — Mobile Engineer
Jul 2025 - Mar 2026
Contributed to ishin, a voice talk room service where AI avatars can join conversations. Worked across three areas: the mobile app, the backend API and the web front end.
Highlights
- Built talk room join UI, ripple animations and AI avatar selection in React Native (Expo SDK 52)
- Designed AI avatar badges, auto-response triggers and a message display queue system
- Implemented follow and block features on both the mobile app and the API
- Built event tracking for room joins and creations via Firebase Analytics and BigQuery
- Handled App Store submission work: App Tracking Transparency, GIF compression and EAS build size optimization
- Optimized OGP image generation in ishin-web (Next.js): 6.6x faster (11s → 1.75s) via font and memory caching
- Developed heartbeat, BigQuery sync and AI avatar management endpoints in the Go backend
Tech stack
linq — iOS Engineer
Apr 2023 - Apr 2024
Joined iOS development for whoo, a location sharing app.
Highlights
- Drove the incremental migration from UIKit to SwiftUI
- Built new features for sending stamps to friends on the map, and messaging
- Implemented interactive animations that encourage user-to-user interaction
Tech stack
SOXAI Healthcare App
Nov 2022 - Mar 2023
Joined mobile development for a healthcare app.
Highlights
- Developed with Quasar, a cross-platform framework
- Designed and implemented the graph screens visualizing health data
nossa360 — Android Engineer
Apr 2020 - Mar 2021
Android development for nossa360, a 360-degree camera app for the construction and real estate industries.
Highlights
- Implemented 360-degree capture using the Camera2 API
- Improved app performance through image processing optimization
- Refined the UI/UX for use on construction sites
Tech stack
Personal Apps
Simple Voice Recorder
iOS / Android
A voice recorder built around one-tap recording. It supports background recording, playlists and recording time on the lock screen, and ships in English, Japanese, Chinese and Spanish among others.
Simple Transcription
iOS
A transcription app that turns speech into text. Recognition runs on device, which makes it practical for recordings and meeting notes.
Voice Narrator
iOS
A text-to-speech app. I built it to try the iOS audio and speech APIs on a real product, and keep improving it based on user feedback.
Japanese Rhyme Finder
iOS
A tool that analyses Japanese rhymes and suggests candidates. I wrote the detection logic myself, based on vowel sequences and tuned for Japanese phonology.