Prove of Kio's innocence (証明！影千代の潔白の巻) is episode 680 of the 1981 anime.
Hattori helps Kagechiyo clear his name when he is accused of stealing Mr Koike's fish.
Mr Koike suspects Kagechiyo
Synopsis[]
Mr Koike is grilling fish outide his flat when the fish suddenly vanishes. He suspects Kagechiyo, who is stroling along the street. Even though Kagechiyo tries to explain his innocence, Mr Koike shouts at him before breaking down.
Later on, at Kemumaki's house, Kagechiyo explains the sticky situation he was in. Kemumaki tells him to remember who was outside, and Kenichi flashes into his mind. Kagechiyo remembers Kenichi taking photographs, so goes to find evidence from him. Kenichi tries to take a photo of him, but finds out that his camera is out of memory!
Meanwhile, Kagechiyo sneaks into the Mitsuba house, but bumps into Kanzo Hattori. Hattori listens to Kagechiyo's problems, and vows to help him. Kagechiyo is delighted. However, they learn from Mrs Mitsuba that they went to a bookshop to have the pictures printed. When they do, they retrieve the roll from Kenichi using violent tactics. Unfortunately, Kagechiyo gets caught red-handed by the shopkeeper, who confiscates the roll of film. Luckily Hattori discovers a picture with evidence - the barbecue that the fish was being cooked on was accidentally dragged off by a motorbike. They then free Kenichi, Shishimaru and Shinzo, who were trapped under the books in the crossfire.
Next morning, Mr Koike learns the truth from the gang, and apologises to Kagechiyo by giving him some fish from his barbecue. Kagechiyo is ecstatic, as is everyone else.