"Famed sword said to have been used by Tachibana Dosetsu, father of Tachibana Ginchiyo, to slice a bolt of lightning in two. In 1548, as Dosetsu napped beneath a tree in his home town of Bungo, a sudden storm swept in and Dosetsu intercepted a lightning bolt with his sword, Chidori.
In reality, of course, even the finest swordsman couldn't possibly cut a bolt of lightning. Thus many interpret the legend as Dosetsu facing off against a Yokai such as a Nue or Raiju. Whatever the case, Dosetsu renamed his sword "Raikiri" (lightning slicer) thereafter, and cherished it as a family treasure.
It passed to his daughter Ginchiyo when he died. It is said that she too told of slicing lightning to her handmaids, meaning that she may have faced Yokai as well."