Sex Friend Nurezakari.

Sex Friend Nurezakari is the story of an old friend, Tsutomu, who pays a visit to a couple then disappears after one night. He leaves behind a mobile phone, and the couple set out to find him and return it. Along the way they meet up with another couple taping themselves having sex. The four of them continue the journey to find Tsutomu. When they arrive at his home, his parents inform them that he was killed in an accident some years previously. What happens next is both bizarre and strangely heart warming as the four friends play a baseball game with the ghost of Tsutomu and thus seal their friendships for good, as all of them discover more about themselves and each other.