In November 1990, Hiroki directed a romance about modern young couples in Japan, "A Love Affair With Sawako" for the Shochiku company. This was followed by the erotic horror V-cinema production "Sadistic City" which took the Japanese Film Section Grand Prize for a video at the Yubari International Fantastic Film Festival. Hiroki's breakthrough into mainstream film, however, came with his 1994 feature "800 Two Lap Runners" which looked at teenage heterosexual and homosexual relationships against a track and field background. The film opened at the Berlin International Film Festival in February 1994 before being released in Japan in July 1994. It placed number 7 on the Kinema Junpo's list of the ten best Japanese movies of 1994.