Ewww:

Long confined to the mountains, Japanese leeches are invading residential areas, causing swelling, itching and general discomfort with their blood-thirsty ways.

[…]

The little suckers are riding into towns and villages, hitching lifts on deer and boar whose numbers have grown due to re-forestation and dwindling rural populations.

[…]

“Yamabiru will climb into people’s socks and stay for about an hour, growing five to 10 times in size. Unlike with water leeches, people don’t immediately realize they’ve been bitten. Only later when they see their blood-soaked feet, do they realize what has happened,” said Shigekazu Tani, the institute’s director.

“The real problem is that the bleeding won’t stop and the affected area swells up and really itches,” he added.