Kotlin Backend Engineer

Japan's largest digital service ecosystem, reaching hundreds of millions of users globally across e-commerce, fintech, and digital media. Joining their central platform group offers developers a rare chance to work with high-concurrency, massive-scale backend infrastructure. Candidates will gain invaluable experience alongside elite international engineering talent, accelerating their careers within a progressive, global-minded Tokyo tech powerhouse.Key ResponsibilitiesDevelop, scale, and maintain core membership Web APIs supporting global platform services.Design and implement secure backend components using Vert.x, Kotlin, MariaDB, and Cassandra.Build essential security services, including user profile management, login alerts, and password verification.Collaborate closely with multicultural engineering teams in an agile development environment.Monitor, troubleshoot, and optimize system performance using OpenCensus and the ELK stack.Required SkillsProven professional development experience with Kotlin and Java focused on Web APIs.Strong experience building scalable APIs using asynchronous frameworks such as Vert.x.Hands-on proficiency with both relational (MariaDB) and NoSQL (Cassandra) database management systems.LanguageEnglish, Japanese, or Chinese: At least one language at an Intermediate LevelBenefitOn-site employee food hall offering provided meals.Work comfortably in a modern, casual dress environment.Maintain a healthy balance through a flexible hybrid model.Receive monthly transportation allowance.Comprehensive health, labor, and employment insurance coverage.