Project Lion - Senior Prompt Engineer - Japan (Remote, Part-Time)
🇯🇵 Japan
Machine Learning
Large Language Models
Data Science
SQL
Analyst
Project Lion - Senior Prompt Engineer - Japan (Remote, Part-Time)
from 🇯🇵 Japan
 We are seeking a Prompt Engineer to be responsible for the end-to-end technical migration workflow for transitioning templates to LLM autoraters. The role is required to use client’s internal tools to leverage prompt engineering techniques to maximize model performance.Â
Responsibilities:Â
Utilize Automatic Prompt Generation (APG) tools to create baseline prompts for complex parent-child template clusters.Â
Run and supervise Automated Prompt Optimization (APO) tool, review the outputs, and flag when the APO reaches deadlocks or plateaus.  Â
Manually draft, test, and refine prompts to navigate complex template architectures, overcome anti-patterns, and handle edge cases where tooling is lacking or broken. Solve edge-case scenarios by designing and refining manual prompts.Â
Monitor shadowbot runs to ensure sufficient disagreements (between human and LLM ratings) are registered, generated, and tracked.  Â
Run prompt versions against established gold data to continuously measure autorater quality against the human crowd baseline, calculating accuracy metrics such as F1 scores, precision, and recall.  Â
Draft technical launch readiness justifications (Launch Certification Documentation) for final.Â
Requirement:Â
Language Skills: Native fluency in Japanese and fluent in English.Â
Location:Â Must be based in Japan.
Education: Bachelor’s, Master’s, or Doctorate degree in Computer Science, Data Science, Computational Linguistics, Human-Computer Interaction (HCI), Cognitive Science, or a related analytical field. Â
Prompt Engineering & AI Expertise: At least 4 years' experience as Prompt Engineer. Proven experience tuning Large Language Models (LLMs) for strict, structured outputs, complex classification tasks, and familiarity with chain-of-thought and few-shot learning. Â
Data Analysis: Strong proficiency in identifying error patterns, analyzing model performance, and using SQL or other data analytics tools. Â
Technical Agility: Ability to quickly learn and master proprietary tools with minimal supervision. Â
Communication: Excellent verbal and written communication skills. Â
Optional / Preferred Skills: Â
Familiarity with enterprise-grade LLM interfaces like the Goose API. Â
Experience in AI model evaluation, data science, computational linguistics, or software engineering. Â
Hands-on experience with Automated Prompt Optimization (APO) systems or tuning workflows. Â
Linguistic expertise, including an understanding of semantics and logic. Â


