Yoshio Kodaira was born on January 28, 1905, in Tochigi, Tochigi Prefecture, Japan. During his childhood, he struggled with a speech impediment known as stuttering. This difficulty in speaking marked his early years. In 1923, when he was 18, he decided to join the Imperial Japanese Navy. He was assigned to a marine regiment based in Yokosuka.

In 1928, Kodaira was sent to China, where he became involved in a military event known as the Jinan incident. During this time, he killed six Chinese soldiers. Reports suggest that he committed other violent acts during his time in China. These include harming many women, with one notable incident where he seriously injured a pregnant woman.

After returning to Japan, Kodaira married but his personal life began to suffer. His wife eventually left him when he had a child with another woman. In 1932, driven by anger, he attacked his wife's family and killed his father-in-law, which led to his imprisonment. He received a 15-year sentence but was released on parole in 1940.

Yoshio Kodaira's criminal story began on July 2, 1932, when he attacked his wife's family. In this violent outburst, he killed his father-in-law and injured six others. He was arrested and sentenced to 15 years in prison but was released on parole in 1940.

Later, between May 25, 1945, and August 6, 1946, Kodaira was responsible for a series of rapes and murders of at least seven women in Tochigi and Tokyo. On May 25, 1945, he invaded a female dormitory at the Navy Clothing Factory and killed a 21-year-old woman. The following month, in June, he raped and strangled a 31-year-old woman near Shin-Tochigi Station. He stole her watch and money afterward.

On July 12, Kodaira invited a 22-year-old woman from Shibuya Station into the woods, promising her a job on a farm. Instead, he murdered her and took her money. A few days later, on July 15, he approached another 21-year-old woman at Ikebukuro Station. He led her to a farmhouse in the woods, where he raped and strangled her before stealing her money and traditional footwear called geta.

Later in September, he again targeted a 21-year-old woman at Tokyo Station, inviting her to the woods where he committed the same crimes. On December 29, he met another 21-year-old woman at Asakusa Station under the pretense of offering a job in a mountain village in Tochigi Prefecture. He murdered her in a similar fashion.

Kodaira's last known murder occurred on August 6, 1946, involving a 17-year-old girl. He had been recruiting her for a job since mid-June and even visited her home to meet her mother. After police discovered her body on August 17, 1946, her parents named Kodaira to the authorities.

Kodaira was arrested on August 20, 1946. During his trial, he denied involvement in three of the murders. He was tried for seven murders on June 18, 1947. After being convicted, the Supreme Court sentenced him to death on November 16, 1948.

Kodaira was executed by hanging on October 5, 1949, at Miyagi Prison in Sendai. On the day of his execution, he stated, "I am fortunate to be able to die on such a calm and peaceful day."