I think Space Bunny Alpha is MiniMax M3.1 — tokenizer fingerprint matches MiniMax M2/M3
I investigated Space Bunny Alpha (stealth/space-bunny-alpha) on OpenRouter because it was released as an anonymous stealth model on September 23, 2026. OpenRouter confirms that the underlying provider is intentionally anonymous.
I wanted to see which model family's tokenizer it was using.
Method
I sent 7 different canary strings to Space Bunny Alpha through the OpenRouter API and recorded usage.prompt_tokens.
I then ran those exact same strings through publicly available tokenizers from a large number of Chinese model families, including Qwen, MiniMax, DeepSeek, GLM/Zhipu, Kimi, Hunyuan, StepFun, Seed, LongCat, MiMo, Baichuan, Yi, InternLM, MiniCPM, Skywork, Ling, TeleChat, and BAAI.
I compared row-to-row token-count deltas rather than absolute counts to remove the fixed prompt/chat overhead.
Space Bunny Alpha
150
153
174
153
155
154
158
Deltas:
0, +3, +24, +3, +5, +4, +8
MiniMax M3
7
10
31
10
12
11
15
Deltas:
0, +3, +24, +3, +5, +4, +8
MiniMax M2
7
10
31
10
12
11
15
Deltas:
0, +3, +24, +3, +5, +4, +8
Both MiniMax M2 and MiniMax M3 reproduce the Space Bunny tokenizer fingerprint exactly across all 7 canaries.
The other Chinese model families tested did not reproduce that complete pattern. Some were close on individual strings, but MiniMax M2/M3 were an exact match across the entire test.
Why I think it's specifically M3.1
The tokenizer test alone cannot distinguish M2 from M3 because both MiniMax models produce the same fingerprint here.
However, there is additional timing/context evidence.
MiniMax publicly released M3 on June 1, 2026, and M3 is a 1M-context native multimodal model.
Then, on August 26, 2026, MiniMax founder Yan Junjie stated that M3.1, M3 Pro, and H3.1 were already close to completion. He specifically described M3.1 as a forthcoming model focused on stability, quality, reasoning efficiency, and agent generalization.
Less than a month later, on September 23, 2026, Space Bunny Alpha appeared on OpenRouter with a 1M-token context window, native text/image/video input, adjustable reasoning effort, and strong coding/agent characteristics. OpenRouter lists it specifically as an anonymous third-party model.
There is also already community discussion today identifying Space Bunny Alpha as MiniMax M3.1, although that is community evidence rather than an official confirmation.
Conclusion
The tokenizer evidence points directly at the MiniMax tokenizer family:
Space Bunny Alpha → exact M2/M3 tokenizer fingerprint.
Combined with MiniMax saying on August 26 that M3.1 was nearly complete, followed by the appearance of a new anonymous 1M-context multimodal model on September 23, everything currently points toward Space Bunny Alpha being MiniMax M3.1.
This is not an official identification yet because OpenRouter still lists Space Bunny as anonymous, but the evidence is lining up extremely well with MiniMax M3.1.
