Photo/IllutrationPolice transport the suspect in the slaying of a well-known blogger from the police box where he turned himself to the Fukuoka prefectural Chuo Police Station at around 11:30 p.m. on June 24. (Amane Shimazaki)

  • Photo/Illustraion

FUKUOKA--Police arrested a suspected Internet troll on suspicion of killing a popular blogger, who criticized him on his blog, after attacking him in a public restroom here in Kyushu.

Hidemitsu Matsumoto, 42, an unemployed man who resides in Fukuoka’s Higashi Ward, was arrested on suspicion of murder and violation of the swords and firearms control law, Fukuoka prefectural police announced on June 25.

The victim, Kenichiro Okamoto, 41, who worked for Tokyo-based Internet security provider Sprout Inc., was also anonymously posting a well-read blog under the user name Hagex.

Okamoto, who lived in Tokyo’s Koto Ward, was visiting Fukuoka to give a lecture as Hagex at a business startup support center, which is sited in a former elementary school building in the city’s Chuo Ward.

Matsumoto was quoted by police as saying, “I held a grudge against him over Internet (exchanges),” and “I thought I would kill him."

According to police, Matsumoto stabbed Okamoto numerous times with a 16.5-centimeter knife in a men’s restroom in the lecture venue on the night of June 24., killing him.

As the suspect repeatedly stabbed the victim about the neck and chest, police believe the attacker had a strong murderous intent.

Police believe the two had never met in person, but they are investigating a possible connection over the Internet.

Under the name of Hagex, Okamoto had posted a number of blog entries about an infamous Internet troll, believed to be Matsumoto. Hagex once condemned the troll for “repeatedly posting slanderous remarks on the Internet.”

Police believe that Okamoto was ambushed around 8 p.m. when he entered the men’s restroom right after concluding his talk, which started from 5:30 p.m. on the day.

Matsumoto fled the scene on a bicycle, but turned himself in at a police box in Higashi Ward at around 10:50 p.m.

On June 25, police seized a bike, which is believed to be the one used by Matsumoto, near a river in Higashi Ward.

While Matsumoto was at large, an anonymous Internet user posted a text at around 10:30 p.m. that suggested the poster's involvement in the slaying.

The poster claimed that he was the infamous Internet troll nicknamed “Teino Sensei” (Mr. Half-wit) by troll hunters, and that he was “now going to surrender himself to take responsibility.”

Police are investigating if Matsumoto actually made the post before turning himself in.

Okamoto’s death publicly exposed Hagex's identity. Hagex’s blog usually quoted a post from an anonymous online textboard and added a brief comment to it. He usually made five to 10 posts each day.

In one post, he commented, “Most people are frightened when they are suddenly verbally abused,” referring to Teino Sansei's trolling.

In the real world, Okamoto was also a well-known figure among Internet security industry circles for writing and publishing articles on cyber-attacks and threats of hackers on websites and magazines.

According to sources, he had expressed his intention to leave his job soon, and establish his own company.

As a blogger, his posts sometimes contained harsh criticism toward the subject.

Haruka Yamazaki, a friend of Okamoto and the representative of a software developer company, said, “I think to a certain extent he was deliberately acting out as a character to stand out on the Internet.

“He had told me that he had concerns that his real name might be connected to his blog when he started his own business. The concerns became a reality.” Yamazaki said with regret.

Ryotaro Okada, president of an Internet security company, who once had been interviewed by Okamoto, said Okamoto's motivation was to “pass on truly valuable information” to readers.

Okada, who is also often invited to give public lectures, said, “I talk while showing my actual name and face, therefore the value of information (in my lectures) is validated.”

“This incident revealed that the threat of anonymous intimidation that will result in a loss to society has become all too real,” Okada said.

(This article was written by Kodai Kinoshita, Amane Sugawara, Amane Shimazaki, Ayana Goda and Tatsuya Sudo, a senior staff writer.)