A 23-year-old Chiba University medical student was sentenced to four years in prison Monday for his role in the gang rape of a woman during and after a party in September last year.

The Chiba District Court ruled that Masaya Yoshimoto, the last of four defendants from the university to be tried in connection with the incident, “bears the heaviest criminal responsibility among those involved.”

Presiding Judge Hideo Nirei said Yoshimoto sexually assaulted the victim, who had become incapacitated after getting drunk, and incited another medical student to commit rape, adding, “The victim seeks severe punishment after sustaining great psychological pain.”

Prosecutors had sought six years for the fifth-year student. His defense team sought a suspended sentence, saying his acts did not involve the use of force.

A 24-year-old former medical student and a 31-year-old former doctor-in-training at the university have already been given suspended sentences in the case.

Another medical student who was in his fifth year, Kensuke Yamada, 23, has appealed after being sentenced to three years in April for gang rape.

The trials of the four men have revealed they were drinking heavily at a party at a restaurant in Chiba on the evening of Sept. 20.

Roughly a dozen people there began binge-drinking together, and the victim was repeatedly asked to compete in drinking contests to empty glasses of wine, according to court hearings.

The men were notorious for their drinking, the court heard, and deliberately wore clothes they didn’t mind staining in case they vomited.

Yoshimoto and Yamada took the incapacitated woman to a women’s bathroom at the restaurant and raped her, while the former doctor-in-training molested her and the 24-year-old former student raped her at his home after the party, according to the trials.

Yamada photographed the woman and sent the picture to others.

“I felt high and did it thinking it was fun,” he said during a court hearing.

“No crime goes unpunished because the assailant was drunk,” warned Ryota Kosai, an Ehime University law professor and an expert on harassment involving alcohol. “Universities must repeatedly call for drinking appropriate amounts of alcoholic beverages.”

In Japan, legislative efforts are under way to impose harsher penalties for rape and other sex offenses. This includes recognizing male rape victims for the first time.

The measure, if passed by the Diet, would raise the minimum sentence for rape to five years from three, expand the scope of the victims and no longer require a victim to file a complaint to prosecute an assailant in cases of rape or sexual molestation.

Despite the enduring impact on survivors of sexual assault, the three-year minimum sentence for rape was shorter than the mandatory five-year minimum penalty for robbery under the criminal code, which was enacted a century ago.

Currently, a victim must first file a complaint to enable criminal prosecution. Removing this precondition is expected to make it easier for rape victims who are reluctant to go public. What impact this would have on the accused remains unclear.

However, deliberations on the bill have not started yet. Given the situation, Justice Minister Katsutoshi Kaneda has vowed to move it forward until the ongoing Diet session ends June 18.