Hiruko the Goblin

Archaeologist Professor Yabe vanishes while investigating a mysterious site soon after writing a letter to his Hieda, his twitchy and easily-frightened colleague. When Hieda finally arrives, he teams up with Yabe’s son to figure out what happened to Yabe and a group of his son’s friends from school. They eventually find the students decapitated and the two of them must confront a hideous monster.
~~ Based on a manga by Daijiro Morohoshi.