Design and operate reliable payment and financial systems, covering transaction integrity, recovery, compliance, cloud infrastructure, and new financial products. The role requires 5+ years of web application experience and leadership across multiple technical domains.
About this role
This practical internship supports technology advancement, platform development, and the foundations used by development teams. The intern will identify technical bottlenecks, consider how product problems can be solved through technology, and pursue fundamental improvements through platform development rather than only implementing requirements. The work may involve full-cycle development, middleware, and infrastructure layers for large traffic and complex domain requirements.
Applicants must have strong technical ability and a track record in a specific technology area sufficient to discuss with and lead professional engineers at an equivalent level. A deep understanding of computer science and a history of continuing hands-on technical exploration are required. Submission of a GitHub account is mandatory. Selection for the MITOU program, completion of Security Camp, core contributions to notable open-source software, and presentations at leading conferences are welcomed examples of concrete technical achievement.
The role supports a platform connecting multiple products and managing and using customer information across them. The business provides digital infrastructure for local shops, including online shop creation, POS, cashless payments, reservations, and an AI management-support application.
Example technologies include Ruby, Ruby on Rails, Java, Spring Boot, Go, AWS, Google Cloud, Cloudflare, RDBMS, MongoDB, Terraform, React, Vue, Next.js, Nuxt, React Router, Swift, SwiftUI, Kotlin, Jetpack Compose, Xcode Cloud, Bitrise, BigQuery, dbt, Metabase, Claude Code, and an internal AI agent based on the Claude Agent SDK.
The internship can begin at any time. The stated period is one month, with participation possible from one week depending on the candidate's schedule and discussion during interviews. Compensation is ¥3,500 per hour. Depending on the period, the arrangement is either an outsourcing contract or part-time employment. The first day includes onboarding training. The role is based in Shibuya, Tokyo, with flextime, a 12:00–16:00 core time, and standard working hours of eight hours. Some roles may require work at specified times outside the core hours, to be confirmed during selection. Indoor smoking is prohibited.
Listed support includes onboarding, one-on-one support from managers or mentors, training and conference participation support, book-purchase support, an internal transfer system, and access to GPT, Gemini, Notion AI, and Claude. Benefits include a ¥5,000 monthly purchase subsidy at STORES shops and member stores, training and conference support of up to ¥50,000 per event with no stated frequency limit, a ¥5,000 monthly book-purchase subsidy, a peer-bonus program, free drinks after 18:00, vaccination support, pregnancy-support leave of up to three months, and childcare support covering up to ¥50,000 per month of the difference for eligible early return after childcare leave. Selection consists of document screening, an optional casual interview, a final interview, and an offer.
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