Mercari is hiring a hands-on Design System Designer for its Design system team. The role supports creation, evolution and governance of the design system across multiple product teams, blending UI craft, systems thinking and collaboration with designers, engineers and brand partners.
What you'll do
- Design, refine and maintain reusable UI components, patterns and guidelines
- Define and evolve design tokens, including spacing, colour and typography
- Ensure platform consistency across Web, iOS and Android
- Drive accessibility and inclusive design practices to support WCAG-aligned standards
- Work with engineers to ensure accurate component implementation and design-code parity
- Partner with product designers to support adoption, identify gaps and ensure alignment
- Collaborate with brand and product design teams to align identity and system architecture
- Create and maintain documentation, usage guidelines and examples
- Establish and improve contribution, versioning and change-management processes
- Lead workshops, training sessions and onboarding for the design system
- Audit product experiences to identify inconsistencies and propose system-driven solutions
- Reduce design and component fragmentation across surfaces
- Continuously evaluate design system performance and future needs
- Explore and experiment with AI tools for system creation, documentation and scalability
- Identify opportunities where AI can accelerate component design, audits, tokens and documentation
- Promote best practices for integrating AI into the design and development workflow
What we're looking for
- 5+ years of experience in product design, UI/UX or design system-focused role
- Strong portfolio demonstrating systems thinking, component design and visual craft
- Deep expertise in Figma, including variants, Auto Layout, tokens and libraries
- Experience working closely with front-end engineers
- Strong understanding of accessibility, responsive design and multi-platform workflows
- Excellent communication skills to explain system logic clearly
- Business-level English
Nice to have
- Familiarity with front-end technologies such as React component libraries, CSS architecture and design token pipelines
- Experience building multi-brand or multi-platform design systems
- Interest in and practical experience leveraging AI tools for design efficiency and scalability
- Business-level Japanese, written and verbal
- Japanese language level A2
Good to know
- Full-time employment status
- Full flextime work hours, no core time
- Office located in Roppongi
- English required at B2 level
- Recruiting cycle: application screening, skill assessment, interviews, reference check, offer