Senior Backend Engineer, Platform Services

KabuK Style, maker of the HafH travel platform, is hiring a Senior Backend Engineer to help design, build, and maintain the core backend services powering KabuK Exchange (KBKx), a new B2B2B travel distribution platform connecting Japanese hotel supply with global demand channels. The role sits within the Commerce Platform area, whose systems ensure every price, booking, payment, invoice, and ledger event is commercially correct and auditable. Work spans pricing service architecture, booking-related financial events, billing and payment workflows, supplier payables and distributor receivables, ledger and reconciliation services, invoice lifecycle management, refunds and credit controls, internal APIs and service-to-service contracts, event-driven workflows, and platform reliability/observability. Responsibilities include designing and maintaining backend services, developing well-documented APIs, translating business requirements into technical solutions, defining service boundaries and data models, improving reliability and monitoring, and reviewing code to support engineering quality across internal and outsourced teams as the platform moves from MVP toward external launch and scale. This is a remote role with preferred locations in Osaka, Fukuoka, or Tokyo, Japan (other Japan locations also welcome), or Seoul, Korea; the role collaborates across Japan/Korea time zones. Employment is as a fixed-term contract employee or via an outsourcing contract, with final terms decided by mutual agreement.