Writing
Born in 1957, Japan. He studied in the Department of Arts of the Yokohama Movie and Broadcasting College. In 1993 he branched out into film, and his movie All Under the Moon(1993) won the prize for Best Screenplay in the Mainichi Film Competition and the Kinema Junpo Award for Best Screenplay. He won several awards for his movie Begging for Love(1998), including the Japan Academy Prize for Best Screenplay, and the First Asia-Pacific Film Festival Award for Best Screenplay. He also won the 2001 National Arts Festival Grand Prize for his TV drama I'll Be Eighteen Tomorrow(2001), and published a collection of essays Andreas's Hat(1995). In 2008, his Japan-South Korea joint production the play Yakiniku Dragon was staged in Tokyo and Seoul.

Tomiko falls in love with Niitaka, even though she also suspects him of being the Tokyo bus driver serial killer, who killed his female conductors after tiring of them.

Benkei, a master fighter and killer, vows never to take another life after his conversion to Buddhism. His faith in pacifism, however, is shaken and ultimately broken by the attacks from a trio of fighters known only as the demons. Taking up his sword once more, he sets out to end their murderous terror.

A gang of thieves plot to rob a US military base in Okinawa, but rising tensions in the group threaten to put the plan in jeopardy.

Men and women caught up in a downward spiral of corruption, discrimination, poverty and death are the focus of this detective-thriller/social-drama inspired by the unsolved 1984 kidnapping of a Japanese candy company president.

A man serving a sentence in a minimum-security prison. Life in the jail is rigid and organized, eventually leading all of the cell-mates to abandon their individuality.

When pregnant lunchbox factory worker Yayoi has finally taken all the abuse she can handle, she strangles her brutish husband and disposes of the body parts, piece by piece. She's soon joined by three down on their luck housewives who murder their own husbands and find various ways to hide the evidence.

During a quest to find a Taiwanese father's grave, disturbing memories of child abuse are aroused.

The members of the Ameya family are all scammers. After their election scheme goes bust in their hometown, they move from Shikoku to Tokyo and resume their fraudulent activities. Everything carries on smoothly until the eldest and the fourth sons' modus operandi go awry, the mother's lover runs off with another woman, and disasters strike one after another. This film is a collaboration between Yoichi Sai and Goro Kishitani following "All Under the Moon." The family business of the Ameya family is defrauding people. The matriarch, who keeps getting married and divorced, has five children with different fathers. The Ameya family chases after fortune and leaves a trail of trouble on their path.

A stage adaptation of the Korean film Parasite, which changes the setting to 1990s Japan. It ran from June 5th-July 2nd 2023 in Tokyo.

Ethnically Korean Japanese filmmaker Yoichi Sai directs this madcap crime comedy. Nakayama (Goro Kishitani) is a suave police detective who doesn't play by the rules. He busts a drug ring, but not before sampling a few of the wares, and he closes down an underaged prostitution ring after enjoying the company of a school girl hooker. One of duties is to shake down sniveling Korean gangster Hideyoshi (Ren Osugi) for information. In spite of their positions on opposite sides of the law, the two discover that they share a fair amount in common. A disregard for the law and the love of a comely prostitute from China named Momo-chan (Makoto Togashi). Though Hideyoshi is running an illegal alien smuggling ring with her and has lusted for her from a far for quite a while, Nakayama manages to bed her first. When she does finally appear in Hideyoshi's bed, she's unfortunately a corpse.

Set in the 1970's in the Kansai region of Japan.. Yong-Gil is Korean, but he moved to Japan and settled down. He runs a small restaurant named Yakiniku Dragon. He is married and has three daughters: oldest daughter Jung-Hwa, middle daughter Yi-Hwa and youngest daughter Mi-Hwa. Oldest daughter Jung-Hwa is dating Tetsuo, but they break up. Middle daughter Yi-Hwa loves Tetsuo and marries him, but Tetsuo still loves her older sister and they divorce. Youngest daughter Mi-Hwa wants to become a singer, but she is in love with a married man.

Set in the 1970's in the Kansai region of Japan.. Yong-Gil is Korean, but he moved to Japan and settled down. He runs a small restaurant named Yakiniku Dragon. He is married and has three daughters: oldest daughter Jung-Hwa, middle daughter Yi-Hwa and youngest daughter Mi-Hwa. Oldest daughter Jung-Hwa is dating Tetsuo, but they break up. Middle daughter Yi-Hwa loves Tetsuo and marries him, but Tetsuo still loves her older sister and they divorce. Youngest daughter Mi-Hwa wants to become a singer, but she is in love with a married man.