Toshi wo Totta Wani Episode 1

A very old crocodile, so old that he had witnessed the building of the pyramids, was suffering from rheumatism, and no longer able to catch his food. In desperation, he decided to eat his great grand son. Although his thousands of years of longevity entitled him to much respect, the family decided he would have to be put down. Unable to bear the disrespect of his family, the old crocodile said goodbye to the Nile. One day the old crocodile met an octopus. The octopus treated her new friend to a variety of fish that she caught just for him. When the night fell, he couldn’t restrain himself from eating one of the octopus’s legs. Since then, the old crocodile began to help himself to the octopus’ leg every night… (Source: AniDB)