What drew such a big crowd so quickly?

A VR-based porn demonstration.

"It was unexpected," said Kento Yoshida, head of the group that organized the event. "But it proved that many people have expectations for VR adult content."

Industry insiders claim that adult VR content may be the key to spreading the technology to the general public, just as it did with videotapes and the internet.

They said VR's potential is huge because it could eventually lead to virtual sex, either with a digital character or a real person in a different location. The technology can also be used to fulfill one's secret fantasies more easily.

While admitting that the erotic possibilities made possible by VR will provoke critics of adult content, they said it will still be meaningful to have a new option for sex.

Yoshida, who is also president of Tokyo-based adult video maker VRG, said most people remain unaware of VR's potential, which is why he held the Akihabara event.