As >>201 speculated, Hachibei is a comic-relief character who is super-famous for his carelessness. Arguably he is the most popular character in the series. For the popularity, the actor, Takahashi Gentaro, had played Hachibei for 30 years (!).

http://uzumaki.cocolog-nifty.com/photos/uncategorized/07061816001.jpg (The second right is Hachibei.)

His famous catchphrase is 「こりゃ、うっかりだ！」(Oh, what a careless mistake I had! or What a blunder! or like that)
Actually Hachibei's family name is unknown. His official name is "Ukkari Hachibei".

http://www1.atwiki.jp/occultfantasy/pages/248.html

>>205
Sigh.. are you still seeking Japanese obscene materials? ┐(´д｀)┌