Blood oath - keppan

The act of putting one's own blood on a signature to emphasize one's sincerity and demonstrate the firmness of one's pledge. This is most common in kishomon (pledges), but can also be found in ganmon (prayer documents), and there is also a similar method known as blood writing, in which blood is mixed with ink and vermilion to write a signature or the text itself. An early example of a blood seal can be seen in the kishomon (pledge) of Kikuchi Takeshige in 1338 (Engen 3, Ryakuo 1) during the Nanboku-cho period, but it became especially common after the Sengoku period, and in the Edo period it was used on kishomon (pledges) issued by vassals to their lords and on kishomon (pledges exchanged between men and women in pleasure quarters). In the early modern period, the proper etiquette was for men to drip blood from the finger of their left hand, and for women to drip blood from the finger of their right hand.

[Chijiwa Toru]

"Studies on Japanese Medieval Ancient Documents" by Ogino Sanshichihiko (1964, Publication Committee for the 60th Birthday of Dr. Ogino Sanshichihiko) " "Christian Faith and Customs" (Okada Akio Collected Works 1, 1983, Shibunkaku Publishing)

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

自己の誠意を強調し、誓約の固さを表明するために、署判の上に自らの身血を付着させること。起請文(きしょうもん)にもっとも例が多いが、願文(がんもん)にも例があり、また、類似のものに、血液を墨・朱に混ぜたもので花押(かおう)を書いたり文章そのものを書く血書という方法もある。血判は早い例では南北朝時代の1338年（延元3・暦応1）菊池武重(たけしげ)起請文などにみられるが、戦国時代以降、とくに多く用いられるようになり、江戸時代には家臣が主君に出す起請文や、遊里の男女の間で取り交わされる起請文にも行われるようになった。近世には、男は左手、女は右手の指の血を垂らすのが作法とされていた。

［千々和到］

『荻野三七彦著『日本中世古文書の研究』（1964・荻野三七彦博士還暦記念論文集刊行会）』▽『『キリシタン信仰と習俗』（『岡田章雄著作集1』1983・思文閣出版）』

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