Japanese traditions - the origin of Kappabashi

Kappabashi is an old street from Asakusa, which once was connecting the two important local temples, the Senso-ji and the Kan'ei-ji from Ueno. Today, Kappabashi is famous for its stores specialized in kitchenware.

Its story starts during the Edo period, when the area was frequently flooded during the rain season, so Kiihachi, a local raincoat merchant, decided to build a channel to drain the water to the nearby Sumida River. The legend says that he wouldn't have been able to finish the construction of the channel without the help of Kappa, legendary water creatures from the Japanese folklore. So, this is the "magical" explanation of the street's name origin...

But there is another explanation, a little more mundane: during the Edo period, raincoats (kappa in Japanese), manufactured by some local low ranking samurai, were frequently displayed on the bridge (bashi in Japanese) crossing the channel. They were making some money that way...
What is the truth? Only the kappa knows... (^_^)