Higurashi no Naku Koro ni Gaiden: Nekogoroshi-hen

The storyline of Nekogoroshi-hen is divided into two parts. The first half consists of average club activities, with the usual members playing poker with embarrassing penalties. In the second half, the club members decide to head to the abandoned Yagouchi Quarry on the outskirts of Hinamizawa. Mion tells the tale of how one of her childhood friends, called Friend A, went missing while playing hide-and-seek near the area. Friend A was found by his father, but they were found dead in their car on the way home when they went off a cliff. It was rumored that they fell victim to the poisonous gases that leaked from the "hole", which supposedly leads to hell.

(Source: Wikipedia)