TOTTORI (Kyodo) -- It was a little before 6 a.m. on Aug. 8, 2023, when Tsutomu Arakawa woke up later than usual to find his wife Yasuko missing.

Over a year has passed since Yasuko, who had been diagnosed with an early-onset type of dementia, disappeared from their home in the western Japan city of Yonago. Her husband Tsutomu is desperately seeking any information on her whereabouts.

The type of dementia she suffers is rare, affecting only 1 percent of those stricken with the disease.

Tsutomu, 65, wishes he had contacted the police earlier, given that he waited until that afternoon to act. Now, haunted by regret, he still puts up missing person posters of his 60-year-old wife and posts messages on social media in the hope she will be found alive.

The shoulder bag and leather shoes Yasuko always wore were gone. She went missing on a Tuesday, when the couple would usually visit their neighborhood supermarket at 8 a.m. for its weekly sale.

When Yasuko had wandered before, Tsutomu found her at the store. He thought this time would be the same but she was neither there nor anywhere else nearby.

He had the city use its emergency broadcast system, which can be used to track down dementia sufferers, to no avail.

But Tsutomu remained positive, believing "there is no way I won't find her," he said.

The next day, there was a troubling development in the case. Police came to Tsutomu's residence to show him security camera footage of a person who appeared to be Yasuko walking toward the city of Matsue in neighboring Shimane Prefecture where her parents live. All promising leads about her location ended there.

The couple's home city of Yonago, in Tottori Prefecture, is near the border of the two prefectures and about 30 kilometers from Matsue, Shimane's capital. There was a report of a sighting of a woman fitting Yasuko's description entering the yard of a private home in the city of Yasugi, but no video camera footage.

Yasuko experiences symptoms of semantic dementia, a rare, progressive type of the brain disease that causes a loss in the ability to understand the meaning of words and other stimuli.

According to Katsuya Urakami, a professor in the Faculty of Medicine at Tottori University, the disease often occurs in people in their 50s and 60s, much younger than dementia usually surfaces.

Yasuko was diagnosed in 2021. Her eldest son realized something was wrong when she described a crow she had seen as "the black thing."

Unlike wandering, which is often a problem for Alzheimer's sufferers, patients with semantic dementia repeat predetermined behaviors. Professor Urakami described the case of the missing woman as "very rare."

Even after her diagnosis, Yasuko retained some independence and would take 20-minute walks alone in the evening along a set path or cook breakfast of bread and eggs. Even so, Tsutomu quit his job last July to dedicate himself to her care.

The day before she went missing, Tsutomu had discussed with carers measures to ensure his wife's wellbeing. They had proposed placing a global positioning system tracking device inside her shoe.

He is tormented by certain thoughts: If only he had contacted the police immediately; if only he had made her carry her ID card.

"I am still full of regrets," Tsutomu said.

The National Police Agency reported in July that a record 19,039 people with dementia or suspected dementia were reported missing to the police nationwide in 2023. The number increased by 330 from the previous year, the 11th consecutive year of increase.

More than 11,000 were over 80 years old, nearly 7,000 in their 70s, and close to 1,000 in their 60s or younger. Amid Japan's graying population, the number of reported dementia sufferers or suspected sufferers missing has doubled over the past decade.

Tsutomu believes it is important that people with dementia "not be forced to do what they don't want to do." Tsutomu regrets doing just that as he had put Yasuko into adult daycare before he quit his job, despite knowing she opposed the arrangement.

He printed new missing person posters with photos of Yasuko in the spring, asking attendants to display them at Shimane train stations as well as convenience stores, gasoline stations and other prominent places.

Tsutomu posted on X, formerly Twitter, "There must be clues out there," but so far there have been no leads. At home alone, he still awaits her return. "I just want her to come back to me unharmed," he said.

(By Ayumu Abe)