Senior Fullstack Engineer (Bilingual –Japanese/English)

Tokyo
Partial Remote
Full-time
July 28, 2025

Job Summary

BizClo is an enterprise-focused LINE chat SaaS platform handling a massive volume of messages and high-traffic request processing daily. The product delivers experiences that improve operational efficiency and drive sales through 1-to-1 communication. In this role, you will tackle challenges such as modernizing and refactoring increasingly complex internal and customer-facing features, improving developer experience, balancing real-time responsiveness with system stability, and paying down technical debt.

Key Responsibilities

Architecture Design
Drive system design and development with an emphasis on modularity and reusability to accommodate flexible customer requirements. Actively work on design improvements based on current architecture and challenges.

Performance & SRE
Lead continuous improvements based on various metrics to enhance service responsiveness and stability, and establish and execute operational indicators.

Design System Promotion
Manage a shared foundation that connects design and implementation while maintaining UI quality.

DevEx Improvement
Improve developer experience by shortening build times, refining review processes, and expanding automation.

Technical Leadership
Facilitate environments that support technical decision-making and actively support the growth and mentoring of junior members.

Multilingual Communication
Collaborate and document effectively with global teams using both Japanese and English.

Language and Platform

TypeScript
Node.js / pnpm / Turborepo

Front-end

Next.js
Chakra UI / ShadCn

Back-end

NestJS
Prisma ORM
Kafka、Redis、Elasticsearch

Infrastructure and Operations

AWS（S3、Cognito、SQS）
Terraform、GitHub Actions

Monitoring and Quality Assurance

New Relic、OpenTelemetry
Jest、Playwright、ESLint、Prettier

Requirements

Extensive practical experience (around 5+ years) in developing medium to large-scale web applications
Experience designing, implementing, and operating UI using React + Next.js
Experience designing and operating scalable backend systems using Node.js + TypeScript
Understanding of datastore design including RDB, NoSQL, and message queues
Experience with DevOps practices utilizing CI/CD and Infrastructure as Code (IaC)
Ability to conduct technical discussions and create documentation in both Japanese and English

Nice to haves

Experience leading improvements in development infrastructure, performance, and monitoring
Experience designing and improving real-time processing for high-traffic systems - Practical experience complying with security and privacy guidelines and regulations
Track record of external contributions (OSS, conference presentations, technical blogging)

APPLY NOW ➜Japanese Required ⚠️

About Mico

Mico's goal is to help companies build their brand through the power of conversation.

They are developing multiple products to analyze and improve communication between businesses and consumers, enabling businesses to optimize their online marketing efforts.

The conversational commerce (C-commerce) is a rapidly growing market, projected to surpass the e-commerce market in some countries by 2025.

Mico (formerly Micoworks) has already achieved 500% business growth in just two years, placing them at No.1 in LINE marketing within Japan. They’ve also secured a total of 6.3 billion yen in funding (with the recent Series B raising 3.5 billion yen).

Mico has set an ambitious goal to become Asia’s No.1 Brand Empowerment Company by 2030, with a clear vision for global expansion. Achieving this goal will require tackling numerous obstacles, and they’re looking for team members who are up to the challenge.

Here are the services you’ll be working on:

Mico Engage AI
A platform that enables seamless communication through message automation and deep integration with client systems.
Mico Voice AI
A service that enhances communication quality and efficiency using AI voice recognition, helping create meaningful connections.
BizClo
An enterprise messaging solution leveraging LINE, optimized for business use to improve customer relationships and internal efficiency.
Micomii
A LINE-based membership service for restaurants, enabling customer segmentation, rank-based perks, and digital coupons.

Why Work at Mico

Flexible work style: Hybrid work, flex time, and up to 6 Life-Health leave days per year to support diverse lifestyles.
Robust growth support: Subsidies up to ¥55,000/year for books and seminars, supporting personal skill and career development.
High transparency: Weekly TGIM meetings and quarterly company-wide updates to share vision and goals.
Leadership training: Strengthening team leadership and organizational management skills through training.
Fair evaluation system: OKRs-based performance reviews conducted semi-annually with continuous feedback.
Social impact: Contributing to clients’ business and workstyle transformation through innovative SaaS products.

Team Culture

Mico leadership and team embody an "OPEN MIND" approach, fostering open and inclusive communication across all levels.

Driven by a strong "ALL FOR ONE" spirit, team members work closely together, both internally and externally, with a "Giver Mindset" at the core of their collaboration.

Surrounded by highly motivated colleagues, you’ll find daily inspiration and opportunities for personal and professional growth.