Fugu Ultra vs Claude Fable 5
Benchmarks, API Token Pricing, Context Window & Speed Comparison
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Fugu Ultra by Sakana AI and Claude Fable 5 by Anthropic represent two of the frontier AI models analyzed in our comprehensive 2026 AI benchmark and LLM comparison. In this head-to-head evaluation, we examine API token pricing, context window specifications, inference speed (tokens per second), and empirical reasoning performance. From a pure economic perspective, Fugu Ultra holds a notable pricing advantage for token ingestion. On output generation, Fugu Ultra is more economical per million generated tokens. In data-heavy architectures requiring extensive repository or document analysis, both models provide an identical memory horizon with 1,000K tokens. In latency-sensitive production environments, Fugu Ultra leads in tokens-per-second throughput, making it ideal for real-time conversational agents and high-concurrency workflows. Below is the complete empirical head-to-head breakdown across cost, speed, context, and capability matrices.
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Fugu Ultra
Premium ReasonerSakana AI's Japanese-multilingual frontier reasoning model developed using evolutionary model merging with million-token capacity.
$1.50 / 1M
$6.00 / 1M
1M tokens
N/A
Claude Fable 5
Mythos-Class CreativeAnthropic's specialized mythos-class creative and literary intelligence titan, delivering extraordinary stylistic nuance, long-form coherence, and rich narrative depth.
$10.00 / 1M
$50.00 / 1M
1M tokens
76.5%
Key Differences at a Glance
- Fugu Ultra is 7.8x cheaper for API usage (input + output tokens combined).
- Fugu Ultra is faster at 75 tok/s vs 52 tok/s.
| Feature | Fugu Ultra | Claude Fable 5 |
|---|---|---|
Intelligence Index Composite reasoning & knowledge score (0-100) | 86 | 72 |
Provider | Sakana AI | Anthropic |
Input Price Cost per million input tokens | $1.50 / 1M | $10.00 / 1M |
Output Price Cost per million output tokens | $6.00 / 1M | $50.00 / 1M |
Blended Price Weighted 7:2:1 cache:input:output per 1M | $1.01 / 1M | $7.70 / 1M |
Context Window Maximum input + output tokens | 1M tokens~1,500 A4 pages of text | 1M tokens~1,500 A4 pages of text |
Max Output Tokens Per single request | 16K | 128K |
Throughput Speed Tokens generated per second | 75 tok/s | 52 tok/s |
SWE-bench Verified Real-world software engineering | N/A | 76.5% |
GPQA Diamond Graduate-level reasoning | 67% | 79.2% |
Cached Input Price Prompt caching discount per 1M tokens | $0.15 / 1M | $1.00 / 1M |
Who Wins Where?
At-a-glance decision frameworkEvaluations ongoing
Empirical Head-to-Head Benchmark Scores
Official evaluation metrics verified by independent third-party research labs.
Industry benchmark evaluating real-world GitHub issue resolution and multi-file debugging.
Challenging questions created by domain experts to test complex PhD-level reasoning.
Hardened reasoning and academic knowledge benchmark with reduced lucky-guess probability.
Crowdsourced human preference evaluation based on blind, head-to-head model battles.
Autonomous multi-step tasks executed inside a real command-line terminal environment.
Tokens emitted per second during active generation streaming.
Latency & Response Time
Time to first token (TTFT) and estimated end-to-end response time for a typical 500-token response.
Real-Time Interactive Token Cost Simulator
Adjust sliders to calculate projected monthly cloud API spending with prompt caching discounts.
Fugu Ultra · Strengths & Key Advantages
- World-class Japanese language comprehension and cultural nuance
- Evolutionary model merging techniques yield creative, non-standard problem-solving paths
- Massive 1M token context window with reliable factual recall
Considerations & Trade-offs
- Higher commercial API pricing reflecting premium research tier
- Niche availability outside the Japanese enterprise market
Claude Fable 5 · Strengths & Key Advantages
- Peerless narrative coherence and creative prose generation across 1M context
- Deep contextual empathy and nuanced psychological analysis
- Sophisticated world-building and multi-character dialogue consistency
Considerations & Trade-offs
- Substantial premium pricing ($10 in / $50 out per 1M tokens)
- Strict 30-day enterprise data retention requirements sparked privacy discussions
- Coding performance is slightly subordinated to prose and conceptual reasoning
Token Use & Task Economics
Estimated cost and token consumption to complete one representative agentic task.
| Metric | Fugu Ultra | Claude Fable 5 |
|---|---|---|
Cost per Task Estimated USD to finish one task | $0.28 | $10.97 |
Output Tokens / Task Tokens generated per task | 22K | 72K |
Reasoning Tokens / Task Thinking tokens burned per task | 8K | 37K |
Technical Specifications
Architecture, release timeline, capabilities, and modalities.
| Feature | Fugu Ultra | Claude Fable 5 |
|---|---|---|
| Official API Model ID (SDK) | fugu-ultra | claude-fable-5-20260601 |
| API Protocol | Sakana AI REST API (OpenAI-Compatible) | Anthropic Messages API + AWS Bedrock + Vertex AI |
| Release Date | 2026-06 | 2026-06 |
| Knowledge Cutoff | March 2026 | March 2026 |
| Architecture | Evolutionary Multi-Model Merged Transformer | Mythos-Class Dense Reasoning Architecture |
| Parameters | Confidential / Frontier Merged | Confidential |
| Enterprise Rate Limits (RPM / TPM) | 5,000 – 15,000 RPM (Production Tier) · 4,000,000 – 10,000,000 TPM | 4,000 – 10,000 RPM (Tier 4 + Priority Tier) · 4,000,000 – 10,000,000 TPM |
| Long-Context Tier (>128K/200K) | Flat rate ($1.5/1M in) across full 1000K window | Standard rate up to 200K tokens; 2x input/output tier above 200K tokens |
| Prompt Cache Policy & TTL | Cached input at $0.15/1M tokens | $1/1M cached read (90% off); 5-min default & 1-hour extended TTL |
| Computer Use / GUI Agent | API / CLI Tool-Use & DOM Agent ready (no raw pixel desktop click loop) | Supported (Screen coordinate grounding, browser & desktop GUI action loops) |
| MCP & Parallel Tool Calling | Native MCP Client/Server ready · Parallel function calling · 100% Strict JSON Schema | Native MCP Client/Server ready · Parallel function calling · 100% Strict JSON Schema |
| Web Search Grounding & Sandbox | Supported via external Tavily/Exa Search & E2B/Docker Sandbox tools | Native Web Search Citations + Code Execution Tool + MCP Connectors |
| Official Fine-Tuning Support | API Prompt Engineering & RAG Distillation | Custom Model Tuning via Amazon Bedrock & Prompt Distillation |
| Multimodal Token Billing | Text BPE (~4 chars/token) | Text BPE (~4 chars/token) · Vision (~258–765 tokens per image tile) |
| Quantization & Min GPU VRAM | Cloud-Hosted Proprietary (FP8 / BF16 Tensor Core Cluster) · Zero Local VRAM Required (100% Serverless Cloud API) | Cloud-Hosted Proprietary (FP8 / BF16 Tensor Core Cluster) · Zero Local VRAM Required (100% Serverless Cloud API) |
| Safety & Frontier Classification | Sakana AI Production Safety & Alignment Verified | Anthropic RSP ASL-2 / ASL-3 Constitutional Safety Evaluated |
| Enterprise Compliance (ZDR/HIPAA/SOC2) | SOC2 Type II · GDPR · Zero Data Retention (ZDR) & HIPAA BAA Available on Enterprise Tier | SOC2 Type II · GDPR · Zero Data Retention (ZDR) & HIPAA BAA Available on Enterprise Tier |
| Input Modalities | text | text, vision |
| Output Modalities | text | text |
Fugu Ultra vs Claude Fable 5: Quick Answers
Which is more intelligent, Fugu Ultra or Claude Fable 5?
Fugu Ultra is more intelligent. It scores 86 compared with 72 on the composite Intelligence Index.
Which model is faster?
Fugu Ultra is faster, generating 75 tokens per second compared with 52 tokens per second.
Which model is cheaper to run?
Fugu Ultra is cheaper at $1.01 per 1M tokens blended, compared with $7.70 (7:2:1 cache:input:output ratio).
Which model has lower latency?
Fugu Ultra has lower latency, with a time to first token of 0.54s compared with 1.75s.
Verdict
Verdict & Model Selection Recommendation: Choose Fugu Ultra if your priority is Japanese enterprise intelligence, bilingual translation, and creative scientific exploration. Its performance in demanding tasks justifies its operational token cost. Choose Claude Fable 5 if your workflow prioritizes Literary authorship, complex screenwriting, video game narrative trees, and high-end marketing campaigns. For large-scale batch processing or customer-facing conversational interfaces, its balance of speed and economics delivers superior ROI.
Frequently asked questions
How does Fugu Ultra compare to Claude Fable 5 in API token pricing and cost per token?+
Fugu Ultra costs $1.50 per 1M input tokens and $6.00 per 1M output tokens, whereas Claude Fable 5 costs $10.00 input and $50.00 output. Overall, Fugu Ultra is the more cost-effective model for high-volume API pipelines. Both models support prompt caching discounts of up to 90% for repeated prompt prefixes.
Which model has a larger context window: Fugu Ultra or Claude Fable 5?+
Both Fugu Ultra and Claude Fable 5 offer an identical context window of 1,000K tokens (~750k words). Both architectures provide equal capacity for large document ingestion, multi-file codebases, and extended multi-turn conversation histories.
Which AI model is better for software engineering and coding: Fugu Ultra or Claude Fable 5?+
Fugu Ultra scores at the frontier of coding benchmarks, while Claude Fable 5 scores 76.5%. For complex autonomous debugging and agentic engineering, Claude Fable 5 provides robust code generation and tool calling.
What is the difference in reasoning capability and extended thinking between Fugu Ultra and Claude Fable 5?+
Fugu Ultra features native chain-of-thought extended thinking mode with configurable reasoning effort. In contrast, Claude Fable 5 provides chain-of-thought reasoning depth for complex math and science.
How does inference speed (tokens per second) compare between Fugu Ultra and Claude Fable 5?+
Fugu Ultra generates approximately 75 tokens per second, while Claude Fable 5 delivers 52 tokens per second. In latency-sensitive production environments, Fugu Ultra provides faster time-to-first-token (TTFT) and higher streaming response velocity.
Can you implement a tiered LLM routing setup combining Fugu Ultra and Claude Fable 5 to optimize costs?+
Yes! High-efficiency architectures route high-frequency routine classification and conversational tasks to Fugu Ultra to save operational costs, and dynamically escalate complex architectural queries or reasoning tasks to Claude Fable 5. This tiered routing pattern cuts overall API bills by up to 70%.
Understand key metrics like context window, token pricing, reasoning mode, and SWE-bench scores in our comprehensive AI glossary.
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Benchmark scores, token prices, and rate limits evolve rapidly as AI labs release model updates. Always verify current specifications and pricing on the official provider documentation.
Sources: GetInfoUs Independent AI Benchmarks & Official API Specs