What is in the water in Japan?

Err, maybe that was a bad question to use as a headline, because a leg was found in a Tokyo river on Monday. But that pales in comparison to this.

A teenage Japanese boy has been arrested after walking into a police station carrying a severed human head and claiming to have killed his mother.

The 17-year-old went to a police station in the town of Aizuwakamatsu, north of Tokyo, carrying the head in a sports bag, Japanese media said.

The beheaded body of a woman was later found at the boy's home, police said.

Japan has been in the news for a number of shocking murders recently. That's something you don't hear much of out of that country.