Players of Sassen wield mock swords, not unlike the lightsabers in the "Star Wars" movies, that are fitted with sensors and emit various colours depending on the situation to hand. When the sword is idle, it glows green. But tapping on it twice brings out a rainbow of hues. A blue ray is emitted when the sword is swung and turns red on contact with an opponent. Competitions and trial use of the special swords are held weekly in a building in Tokyo's Akihabara district, a centre of Japanese popular culture in Chiyoda Ward that is also famed for its stores selling the latest in digital gadgets. Among those who gather for the events are fans of battle manga as well as kendo enthusiasts. Mamina Miyakawa, 34, who works for an information technology company, began Sassen about two years ago because of its slogan of integrating IT with chanbara.