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GPT-6 Luna is the fast, low-cost tier of OpenAI's GPT-6 series (1.05M-token context, text, image, and file input, $0.10/$0.50 per million input/output tokens), released September 22, 2026 below GPT-6 Sol and the flagship GPT-6 Astra. It is built for high-volume tasks with a clear goal, such as summarization, extraction, classification, quick questions, and lightweight agentic steps.

Fugu Ultra v2 is the higher-performance tier of Sakana AI's Fugu family: rather than a single trained checkpoint, OpenRouter describes it as a learned multi-agent orchestration system that routes each request across a pool of models, exposed here with a 1M-token context. It is proprietary and priced at the top of the Fugu line, aimed at the hardest coding, reasoning, and tool-use tasks where Fugu Max's lower cost is not enough.