Watanabe no Tsuna (渡邉綱) (role 953 – 1025)
The Four Guardian Kings in Buddhism are called the shitennō. This same term in time came to be applied to the four lieutenants of Raikō, one of whom was Watanabe no Tsuna. But Noriko Reider points out in her Seven Demon Stories from Medieval Japan that Tsuna was not mentioned in the Konjaku monogatari which was compiled about 100 years after Raikō's death nor in any other Heian literature (794-1185).
Reider continued: "When it comes to the supernatural episodes, Tsuna attracts oni as much as Raikō does. ...according to the “Swords Chapter” of the Heike monogatari (Tale of the Heike, thirteenth century), for example, Tsuna encounters an oni and severs his hand. Tsuna also plays an important role in fighting another supernatural creature, an earth spider.
From medieval times on, Watanabe no Tsuna (953–1025) is known as Raikō's right-hand man and the leader of Raikō's shitennō. Sonpi bunmyaku also notes that Tsuna was the most eminent of Raikō's shitennō (Tōin 3:14). Any relevant entry in a dictionary would make the same points. As mentioned earlier, however, Tsuna's name does not appear in any Heian literature. He is the newest member of the shitennō in both historical and fictional documents.
Tsuna's name emerges for the first time in Kokon chomonjū (A Collection of Ancient and Modern Tales That I've Heard, 1254), written by Tachibana no Narisue more than two centuries after Tsuana's death..." It isn't until the story 'Minamoto no Raikō Kill the Demon Boy' that Tsuna appears "...with Sadamichi, Suetake, and Kintoki, and they are identified as Raikō's shitennō."