Born in Tokyo in 1947. Arai is the editor and publisher of the quarterly magazine Eiga Geijutsu. After working as an assistant director at Wakamatsu Productions, he debuted as a screenwriter in 1977 with Shinjuku Messy District: I’ll Be There. Since then, he has written screenplays for many classic Nikkatsu pink films and has become one of Japan’s leading screenwriters. His screenplays include those for Shinichiro Sawai’s W’s Tragedy (1984), Ryuichi Hiroki’s Vibrator (2003), and Shinji Aoyama’s The Backwater (2013), for which he was awarded the Kinema Junpo Award for Best Screenplay. He also wrote and directed Body and Soul (1997) and When I Was Most Beautiful (JC 2015).