Project Lion - Senior Prompt Engineer - Japan (Remote, Part-Time)

19 hours, 48 minutes ago
Freelance
Senior
Data Science and Analytics
Welocalize

Welocalize

Welocalize provides translation and localization services to help businesses reach global audiences with precision and efficiency.

Professional Services
1K-5K
Founded 1997
$34M raised

Description

  • Use Automatic Prompt Generation (APG) tools to create baseline prompts for complex parent-child template clusters.
  • Run and supervise Automated Prompt Optimization (APO) workflows, review outputs, and identify deadlocks or plateaus.
  • Manually draft, test, and refine prompts for complex template architectures and edge cases where tooling is insufficient.
  • Design and refine manual prompts to solve difficult edge-case scenarios.
  • Monitor shadowbot runs to ensure disagreements between human and LLM ratings are generated and tracked.
  • Run prompt versions against gold data to measure autorater quality against the human crowd baseline.
  • Calculate evaluation metrics such as F1 score, precision, and recall.
  • Draft launch readiness justifications and certification documentation for release approval.
  • Use client internal tools to support the end-to-end technical migration workflow.

Requirements

  • Native fluency in Japanese and fluent English.
  • Must be based in Japan.
  • Bachelor’s, Master’s, or Doctorate degree in Computer Science, Data Science, Computational Linguistics, HCI, Cognitive Science, or a related analytical field.
  • At least 4 years of experience as a Prompt Engineer.
  • Experience tuning LLMs for strict, structured outputs and complex classification tasks.
  • Familiarity with chain-of-thought and few-shot learning approaches.
  • Strong ability to identify error patterns, analyze model performance, and use SQL or other data analytics tools.
  • Ability to quickly learn and master proprietary tools with minimal supervision.
  • Excellent verbal and written communication skills.
  • Preferred: familiarity with enterprise-grade LLM interfaces such as the Goose API, AI model evaluation, data science, computational linguistics, or software engineering experience, hands-on experience with APO systems or tuning workflows, and linguistic expertise including semantics and logic.

Interested in this position?

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