sarashina2.2-Bi-0.5b

Overview

sarashina2.2-Bi-0.5b adapts sbintuitions/sarashina2.2-0.5b into an LLM2Vec-style bidirectional encoder with roughly 0.5B non-embedding parameters, delivering Japanese sentence representations.

Hugging Face Collection
GitHub

Usage

Requirements

sentence-transformers>=4.1.0
transformers>=4.51.0
accelerate>=1.6.0
sentencepiece>=0.2.0
flash-attn>=2.7.3

Sample Code

import torch
import torch.nn.functional as F
from transformers import AutoModel, AutoTokenizer

model_name = "iamtatsuki05/sarashina2.2-Bi-0.5b"
model_kwargs = {
  "torch_dtype": torch.bfloat16,
  "attn_implementation": "flash_attention_2",
  "device_map": "auto",
  "trust_remote_code": True,
  "use_auth_token": True,
}
tokenizer = AutoTokenizer.from_pretrained(model_name)
model = AutoModel.from_pretrained(model_name, **model_kwargs)

queries = ["ハチワレはどのようなキャラクターですか？"]
docs = [
    "ハチワレは、『ちいかわ』に登場する猫風のキャラクターで、明るく社交的、前向きな性格が特徴。ちいかわたちと共に日常を楽しみつつ、討伐などの冒険にも積極的に挑む存在です。",
    "うさぎは、天真爛漫でマイペースな性格が特徴のキャラクターで、突飛な行動力と鋭い直感でちいかわたちを引っ張る存在。自由気ままながらも仲間思いな一面を併せ持ちます。",
]
q_emb = model.encode_query(queries, tokenizer)
d_emb = model.encode_document(docs, tokenizer)
scores = F.cosine_similarity(q_emb, d_emb)
print(scores)

Model Details

Base model: sbintuitions/sarashina2.2-0.5b
Architecture: Llama
Maximum sequence length: 8,192 tokens
Embedding dimension: 1280 (mean pooling)
Tokenizer: SentencePiece / vocabulary size 102,400
Positional encoding: RoPE
Supported languages: Japanese
Similarity metric: cosine

Licence

This model is distributed under the MIT License.

How to Cite

@article{MIREI
  title={同一条件下における Encoder/Decoder アーキテクチャによる文埋め込みの性能分析},
  author={岡田 龍樹 and 杉本 徹},
  journal={言語処理学会第 32 回年次大会 (NLP2026)},
  year={2026}
}