Warriors would sometimes adorn themselves with symbols that acted like talismans to protect themselves from harm or prayer for victory. The tsuba or sword guard was a favorite item for the samurai to personalize with these symbols.
One such symbol of protection was Shoki or "Demon Queller." Shoki (鍾馗) is a Taoist deity who was a popular art motif around the Edo period and is supposed to protect against evil.
As the story goes, Shoki was a promising young physician who dreamed of being a physician at the imperial palace. He took the government service examination and scored 1st place. When he was presented to the court to receive his award, the Emperor rejected him because of his extreme ugliness. After being cast out, Shoki committed suicide. Upon hearing about Shoki taking his own life, the Emperor overcome with guilt posthumously awarded him the title of Doctor of Zhongnanshan which is supposed to be the birthplace of Taosim and ordered him buried in imperial green. Shoki's spirit, in appreciation, vowed to protect the Emperor from evil and thus became canonized as Shoki the Great Spiritual Chaser of Demons. He is usually depicted wearing boots, a large scholars hat, wearing a green robe and carrying a sword while he is either stabbing or trampling on demons.
In Japan, Shoki is usually associated with Boys day and is supposed to watch over children and protect them from evil and illness. Shoki is also a very popular symbol in Kyoto where he is used to protect buildings, temples and even protect against fire.