Burial of the Rats (2007)

After his girlfriend disappeared mysteriously, Alex is wandering Tokyo desperately looking for clues about what happened to her. One day he receives an anonymous message telling her she was last seen near the dreaded Jukai forest, where few people ever return. With only this clue in hand and nowhere else to turn, he ventures into the dark woods in the slim hope of finding his girlfriend. But the horrors that lurk ahead is beyond anything he could have ever imagined. Will Alex find the truth before he loses his sanity?