src/transformers/models/gpt_neox_japanese/tokenization_gpt_neox_japanese.py/GPTNeoXJapaneseTokenizer/vocab_size
class GPTNeoXJapaneseTokenizer:    def vocab_size(self):
        # self.vocab contains support for character fluctuation unique to Japanese, and has a large number of vocab
        return len(self.raw_vocab)