It is said that Kumanobetto Tanzo (or Bensho in "Gikeiki" and Benshin in "Benkei Monogatari," one of the stories in the Otogi Zoshi picture storybook) abducted a daughter of a noble having a rank of Nii Dainagon (Second Rank, chief councilor of state), and Benkei was the boy born to her and Tanzo.
熊野別当湛増（『義経記』では「弁しょう」、『弁慶物語』では弁心）が、二位大納言の姫を強奪して生ませたとされる。