Empero releases Qwythos-9B trained on Claude traces

Laboratory Empero has introduced Qwythos-9B, a reasoning model based on Qwen3.5-9B, fine-tuned on over 500 million tokens of Claude Mythos and Claude Fable traces. The model uses full-parameter fine-tuning and is released under an Apache 2.0 license.

Using the lm-evaluation-harness, the model outperforms the base Qwen3.5-9B: +34.3 points on MMLU (0.575 vs 0.232), +30 points on gsm8k-strict, and +19 on gsm8k-flex. On gpqa_diamond, the result is 5 points lower than the base model.

The context window is extended to 1,048,576 tokens via YaRN rope-scaling with a factor of 4, built on top of the native 262,144 tokens. It includes native function calling: in a 7-prompt test involving a Python executor and web search, the model provided correct answers with links in every case.

The model is intentionally uncensored and optimized for cybersecurity, biomedicine, and pharmacology. Weights are available on Hugging Face.