Refers to the traditional Chinese male hairstyle where the front is shaved and the back hair is braided into a long pigtail, historically associated with the Qing dynasty.
Men in the Qing dynasty wore a queue.
You see characters with a pigtail in period dramas.
Contains outdated kanji; rarely used today.
From Chinese 辮髮 (biànfà), meaning 'braided hair'. The Japanese reading is on'yomi.