A Violent Death on the Last Day of the Year
Haruka Komatsumoto was stalked via a hidden tracker in a plush toy, leading to a fatal attack in Japan.On the final day of 2025, while families across Japan were preparing to welcome the New Year, a shocking murder took place in Mito City, Ibaraki Prefecture.
Haruka Komatsumoto, a thirty one year old nail technician who was pregnant, was found brutally killed inside her apartment.
She had married the previous year and lived quietly with her husband.
By all accounts, their life together appeared peaceful and ordinary. 
The Final Hours Before the Attack
On the day of the incident, Haruka and her husband went shopping together shortly after noon and returned home.
Later, Haruka left the apartment again, while her husband went to work.
At around four fifty in the afternoon, she called him and said she was on her way back home.
Just after seven in the evening, her husband returned.
The front door was unlocked.
Haruka was lying in the entryway, still wearing her house clothes and socks.
She was covered in blood and showed no signs of life.
Evidence of Extreme Violence
Police found dozens of wounds and bruises across her body.
Her head showed signs consistent with blunt force trauma.
Investigators also noted multiple defensive injuries on her arms.
These were believed to be attempts to shield her abdomen and protect her unborn child.
There were no signs of forced entry or robbery.
Her wallet and phone were still inside the apartment.
Nothing appeared to be missing.
Based on the scene, authorities concluded that the attack was driven by intense personal resentment and clear intent to kill.
A Quiet Neighborhood Shaken
The apartment complex stood near the Mito Interchange of the Joban Expressway, surrounded by farmland and quiet residential streets.
A nearby resident later expressed anger and disbelief.
She said she usually stayed home on New Year’s Eve and only realized something had happened the following day, when she saw police tape while walking her dog.
She recalled seeing the couple in the building about a year earlier.
They never spoke, but Haruka always nodded politely when greeted.
She described her as slim, well dressed, and understated.
The husband seemed normal, she added.
She had never heard of any conflict between them.
Arrest of a Former Boyfriend
On January twenty first, police arrested a suspect.
He was Haruka’s former boyfriend, twenty eight year old Takumi Ouchi.
The two had met at a restaurant in central Mito.
At the time, Haruka was attending nail school while working part time to save money to open her own salon.
Ouchi was a frequent customer.
After work, he often visited bars and nightclubs.
People who knew Haruka described her as gentle, frugal, and deeply focused on building her future.
A Relationship That Would Not End
The couple began dating in 2024.
Haruka was Ouchi’s first romantic partner.
Their relationship lasted less than a year.
They broke up within the same year.
Between May and June of the following year, Ouchi repeatedly sent messages asking to reconcile.
Eventually, Haruka blocked him on all communication platforms.
For a time, the harassment seemed to stop.
Then, around October, Ouchi began asking others about her address.
The Gift That Became a Weapon
Several days before the murder, a package arrived at Haruka’s parents’ home.
Inside was a plush toy featuring a popular cartoon character.
The recipient name was Haruka’s.
The package listed the sender as the operating company of the theme park associated with the character.
A letter inside claimed it was a prize from a promotional lottery.
The toy was one Haruka loved.
She suspected nothing and brought it back to her apartment.
After her death, police examined the toy.
Hidden inside was a tracking device.
How the Stalking Was Carried Out
Further investigation revealed that the tracker had been transmitting location data directly to Ouchi’s phone.
Police believe Ouchi deliberately chose a plush toy Haruka liked.
He concealed the device inside it and used it to monitor her movements.
Four days before the murder, Haruka made an anonymous phone call to the Mito Police Department.
She asked for advice on how to handle stalking by an ex boyfriend.
Because the call was anonymous, police were unable to take further action.
Haruka’s husband later told friends that they planned to file a formal report after the New Year holiday.
They underestimated the danger.
Surveillance Footage and Denial
Security camera footage showed Ouchi’s car near the apartment around the time of the attack.
During questioning, Ouchi denied all allegations.
He claimed the accusations were baseless and said he knew nothing about the incident.
Tracking Devices and a Growing Threat
Tracking devices are designed to be placed in wallets, bags, or other valuables to help locate them if lost.
One example is Bluetooth tracking devices.
In recent years, however, cases involving their misuse for stalking have increased.
According to the National Police Agency of Japan, consultations related to tracking based harassment numbered one hundred ninety six in 2023.
The figure rose to three hundred seventy in 2024.
In 2025, it reached five hundred ninety two.
Expert Warnings About Hidden Trackers
Akiko Takahashi, a visiting professor at Seikei University, warned people to be cautious when receiving unexpected gifts.
She explained that when a tracker is hidden inside a large, fluffy plush toy, it can be extremely difficult to detect by touch alone.
It is similar, she said, to trying to feel a coin buried deep inside cotton filling.
Former Kanagawa Prefectural Police investigator Tatsuya Narumi emphasized the importance of refusing unsolicited prizes.
He advised people to regularly empty their bags and check for unfamiliar items.
If the object is a stuffed toy, examining the seams is especially important.
Public Fear and Reflection
The case deeply unsettled the Japanese public.
Many online commenters expressed fear, saying that being targeted by such a person leaves no safe place to hide.
Others urged emotional restraint.
They reminded readers that romantic rejection is not the end of life.
Acting on obsession, they said, only leads to irreversible harm.
Some noted that even public figures had once donated stuffed toys they received from fans.
After reading this case, they said, even ordinary people might fear accepting plush gifts from unfamiliar sources.
One comment summed up the collective anxiety.
Each tragedy, the person wrote, adds another lesson.
They no longer trust elevators blindly.
They check traffic even at green lights.
Now, even stuffed toys feel dangerous.
The world, they said, seems filled with risks hiding in plain sight.
