A well-known Japanese blogger and expert on the “dark web” was stabbed to death by an internet user he had clashed with online shortly after delivering a lecture on how to manage online disputes.

Kenichiro Okamoto was reportedly followed to the toilets in the lecture centre in the Chuo district of Fukuoka city, in south-west Japan, at around 8pm on Sunday evening.

Mr Okamoto, a 41-year-old employee of a cyber security consultancy who was better known by his online name Hagex, was found with multiple stab wounds to his chest and neck. He was confirmed dead at a local hospital a short while later.

According to national broadcaster NHK, a man in his 40s surrendered to police about three hours later, telling officers that he “hated” Okamoto and adding: “I am responsible for the murder in Chuo Ward”.

A blood-stained knife was found in the bag carried by the man, identified in other media as a 42-year-old from Fukuoka.

Reports have described the suspect as a “hikikomori”, one of the estimated half-a-million Japanese who have shut themselves off from society and only communicate through their computers.

The suspect reportedly had a history of becoming embroiled in disputes in cyberspace and it is believed that he had argued with Mr Okamoto prior to the incident.