(953–1025) was a Japanese samurai, a companion in arms of Minamoto no Yorimitsu (also known as Raikō), one of the earliest samurai to be famed for his military exploits in a number of tales and legends. Watanabe no Tsuna was the first person to take the surname Watanabe, and Watanabe is the fifth most common surname in Japan, with approximately 1.08 million people as of 2017. Because Watanabe no Tsuna is associated with the legend that he vanquished oni historically considered to be the strongest, such as Shuten-doji and Ibaraki-doji, there is a tradition that oni stay away from people named Watanabe and their houses. For this reason, some families with the surname Watanabe have not practiced the custom of throwing beans on Setsubun for generations. Origin Watanabe no Tsuna was a samurai of the Saga Genji branch of the Minamoto clan, and his official name was Minamoto no Tsuna. He was the son of Minamoto no Atsuru (933-953) married to a daughter of Minamoto no Mitsunaka, grandson of Minamoto no Mototsuko (891-942), great-grandson of Minamoto no Noboru (848-918), and great-great-grandson of Minamoto no Tōru (822-895), son of the Emperor Saga (786-842), the 52nd Emperor of Japan. Tsuna established the Watanabe branch of the Minamoto clan, taking the name from his stronghold at Watanabe, in Settsu Province, and in 1020 he was appointed 'Tango no kami' (Governor of Tango Province). He was the stepgrandson of the Seiwa Genji and Chinjufu-shōgun Minamoto no Mitsunaka (912-997), and was companion in arms to his step uncle Minamoto no Yorimitsu (944–1021). In legend Tsuna features in many of Yorimitsu's legendary adventures, and aids him in fighting many monsters, beasts and demons. In one such tale, Tsuna accompanies Raikō to the hut of Yamamba, a man-eating hag. There they find a boy known as Kintarō, who had been brought up among animals and endowed with superhuman strength. The boy requests that Raikō allow him to become one of his retainers, and Raikō accepts, giving the boy the name Sakata no Kintoki, often shortened to Kintoki. Some of Watanabe no Tsuna's other comrades are Urabe no Suetake and Usui Sadamitsu. Together, the four are collectively known as the Four Guardian Kings, an allusion to the Buddhist Shitennō. Watanabe is also said to have assisted Raikō in slaying a tsuchigumo. His most famous feat is the defeat of the oni Ibaraki-doji, the principal follower of Shuten-doji. He