Zesheng Cai

I'm

About

Holding a Master’s in Information Engineering from Osaka University, I bring over five years of experience in software development. After gaining full-stack experience at Rakuten, I joined KPMG Japan to specialize in backend engineering, focusing on data pipelines, big data processing, and modern API architecture. Recently, I’ve been returning to my machine learning background from graduate research, exploring AI technologies such as building intelligent agents and integrating AI into backend systems to enhance automation and efficiency.

Birthday: 8 Jan. 1996
Phone: +81 090-xxxx-2531

City: Tokyo, JP
Email: saitakusei@gmail.com

Interests

Software Development

Machine Learning

Site Reliability Engineering

LLM

Software Engineering

Visualization

Algorithms

Game

Education

Master of Information Engineering

Apr. 2019 - Mar. 2021

Osaka University

Machine Learning

Bachelor of Computer Science and Engineering

Sep. 2014 - Jun. 2018

Sun Yat-sen University

Computer Vision

Online Certification

CKAD

Cloud Digital Leader

Experience

KPMG FAS

July 2025 - Present

Backend Engineer

Data Pipeline Development: Built and deployed automated data pipelines with Python to collect, transform, and load structured financial data into SQL Server.
Cloud Infrastructure and IaC: Migrated and managed workflows on Databricks using Databricks Bundle for infrastructure-as-code, improving maintainability and operational efficiency.
Big Data Processing: Utilized Apache Spark to process large-scale datasets and integrate results into Databricks Lakehouse for scalable analytics.
API Modernization: Replaced RESTful APIs with GraphQL and implemented ORM, improving efficiency and flexibility in data access.

Rakuten Group, Inc

April 2021 - June 2025

Software Engineer

Frontend Development: Built and maintained web applications using Vue.js and Nuxt.js, including developing new SEO-friendly pages, implementing a multi-application user flow that increased engagement by 35%, and migrating from Nuxt2 to Nuxt3.
Backend & Data Engineering: Developed GraphQL backends with Node.js and MySQL. Built an intelligent item recommendation pipeline using vector embeddings that increased CTR by 25%, and integrated an Elasticsearch-powered car data system achieving 61% classification accuracy.
Infrastructure and CI/CD: Managed GCP with Kubernetes and Terraform, and automated deployments with GitHub Actions to improve release speed and reliability.