One woman, when asked why they think 64 per cent of people in the same age group are not in relationships, said she thought men "cannot be bothered" to ask the opposite sex on dates because it was easier to watch internet porn.
The number of births dropped below one million in Japan for the first time last year, according to the Ministry of Health, Labour and Welfare.
Japan's National Institute of Population and Social Security Research predicts that the country's current population of 127 million will decline by nearly 40 million by 2065.
The fertility crisis has left politicians scratching their heads as to why youngsters are not having more sex.
Comedian Ano Matsui, 26, told the BBC: "I don't have self-confidence. I was never popular among the girls.
"Once I asked a girl out but she said no. That traumatised me.
Comedian Ano Matsui says he was "was never popular among the girls" (BBC)
"There are a lot of men like me who find women scary.
"We are afraid of being rejected. So we spend time doing hobbies like animation.
"I hate myself, but there is nothing I can do about it."
Annual 'Steel Phallus' festival in Japan celebrates the penis
Artist Megumi Igarashi, 45, who once made a 3D image of her own vagina, said "building a relationship is not easy".
"A boy has to start from asking a girl on a date," she told the BBC.
"I think a lot of men just cannot be bothered.
"They can watch porn on the internet and get sexual satisfaction that way."
Facebook
Twitter