It all starts innocently enough, with a quiet spoken apology. "I had a car accident so I'm not as fast as I used to be," says the man known as Nama Chirigami. A hint of what's to come lurks in his appearance, a disorientating mix of salary-man, student and glam rocker: painted nails, combat trousers, waistcoat, and eyeliner topped off with an explosion of dyed red hair. Then the bell rings and verbal blast-off begins.
The target is online bullying. "What the blazes is wrong with the people who post these messages," he bellows. "Why do they say such horrible things?!"
The spectators flinch, then smile and gradually warm to him. Mid-monologue, the bell sounds again signalling time up and Chirigami falls sweating to the floor. As he walks back to his seat, exhausted, the judge yells "next!"
The scene is a packed community hall in Yokohama, outside Tokyo, which is hosting heats for Japan's annual poetry boxing tournament, a decade-old competition that pits opponents against each other in a ring armed with motor-mouths instead of fists.
The aim, says the organiser and president of the Japan Reading Boxing Association, Katsunori Kus-unoki, is to smash inhibitions and pummel shyness.
"Japanese people are self-conscious and don't like to speak out so we try to encourage them to express their opinions and feelings here," he says. An academic when not judging these competitions, Professor Kusunoki says he is worried by the growing lack of face-to-face communication.
"People sit alone on the internet, blogging or posting messages to bulletins. We need to create something more interactive."
Anything is fair game, as long as it stays within the three-minute time limit. Competitors come armed with haiku poems, manga, fairy-tales, mini-dramas, dance and hip-hop set to monologues about everything from politics to natto – Japan's famously smelly fermented bean paste.
The competition draws verbal gladiators from across the nation, and from every layer of Japanese society: students, housewives, the disabled, teachers, salary-men, pensioners. The youngest is 15, the oldest so far was 93, though he never got past a local heat. Some compete year after year.
"I love words and when I saw the competition on TV I really wanted to take part," recalls Yuko Hirata, 22, a regular contestant.
A diminutive, bookish woman who works as a video editor, she judders into life as the bell sounds with a high-energy spiel about being dragged around town by her mother. These heats have helped her get better at expressing herself in public, she believes. "I worried I wasn't good enough but the more I take part the more confidence I get."
Today's best 16 will go to a prefectural heat, where the real verbal combat starts. In a ring with a blue and red corner, pairs of poetry boxers face off in intense three-minute bouts of stand-up verse. Winners must negotiate a series of challenges, including a timed presentation and a Whose-Line-Is-It-Anyway-style improvised joust, prompted by shouted words from the panel of judges.
The heats climax with a November final, where the national champion is crowned, and handed a trophy designed by the cult Japanese artist Kenji Yanobe along with a cheque for 50,000 yen (£240).
Professor Kusunoki believes the annual event will grow in importance as Japan opens up to foreigners, who make up just two per cent of the population.
"Japanese people are used to communicating only among themselves, but we are going to need many more foreign workers as the population of this country falls. How are we going to speak to them?" This year his organisation ran its first English-language competition, attracting mainly literature students. Eventually, the president hopes to try other languages.
Today's poetry boxers, then, could be the vanguard of Japan's multicultural society, but not unfortunately Nama Chirigami, who fails to qualify.
"He'll be back," says Professor Kusunoki.