A Chinese professor at a Japanese university has been missing for about six months since his trip home last year, raising concerns about his safety, the institution said Tuesday.

The apparent disappearance of Chinese literature and linguistics professor Hu Shiyun, who worked at Kobe Gakuin University in western Japan, comes as Beijing has sharpened its focus on its nationals abroad in recent years.

Kobe Gakuin University was first notified in September by Hu's family in Japan that he had been unreachable since his earlier return -- sometime in or after August -- to his homeland, the school's spokesman Yoichi Takamura told AFP.

At the urging of the family, the university initially took no action, but it finally asked the Chinese Consulate General in Osaka earlier this month to investigate his whereabouts.

"We're worried. We hope to hear from him," the spokesman said, adding that as of today, the university had been given no update.

"Had he been Japanese, there would be more things we can do, like contacting police, but since he's a Chinese national, waiting to hear back from the consulate is the only thing we can do at the moment," he said.

On the university's website, Hu is described as having authored academic papers and books in the past including about Chinese language textbooks in Japan and Chinese dialects.

In 2019, Yuan Keqin, a professor at Japan's Hokkaido University of Education, vanished after travelling to China for a family funeral, with China's foreign ministry later saying he had confessed to spying and was in custody.

And in 2013, Zhu Jianrong, a professor at Tokyo's Toyo Gakuen University, was detained by Chinese authorities on suspicion of illegal intelligence-gathering, also after vanishing on a trip home.

The Chinese consulate in Osaka was not immediately available for comment.