Ganon, it bothers me somewhat that you are still talking like your "toddlers included" scenario is a plausible explanation. I typed japan 2015 national fertility survey into Google and literally the first result was a link to the survey's homepage. The first link on that page, "Highlights", which is also the second Google result, contains proof that your idea is totally without merit in this case.
NEVER-MARRIED MALE RESPONDENTS WHO HAVE NEVER HAD INTERCOURSE WITH THE OPPOSITE SEX (2015) on page 6
It literally took me longer to put together that table than it did for me to find the information in it. Why didn't you find it first? Or do you still maintain that your claim has merit?
An equally likely explanation: An additional 40% of young Japanese are homosexual.
you could equally google "what percentage of Japanese are married" and see what % have married and of course consummated the marriage.
According to the 2010 census, 58.9% of Japan's adult population is married,
59% of the population, almost 2/3rds of the entire group surveyed are not included in that result, even if just 16% of the remaining population were having sex that would give you 75% of the actual adult population are having sex, meaning less than 1 in 4 is a sex robot banging weeb in comparison to the "almost half" which the initial click bait headline would try to push.
I wasn't going into the exact study beyond the article Final-Fan I was more interested in the sensational sex robot infested Japan filled with virgins story being incorrect and trying to make a point about how articles like this one either include or remove a group of people to fluff the numbers, in this case the obvious one I missed out on was that 59% of the population there is married and banging, of the remaining 41% of that... 42% are virgins as per the group recorded.
42% of 41% is 17.22% of the age ranges you've listed there are virgins.
Now of those 17.22% who filled out the survey and said they were virgins I'd ask you to consider taking a look at the cultural differences in Japan in some area's of dating , I found a decent read on it (fairly long) but it's interesting none the less.
But the part I was interested in is here at
"Unlike the West, Japan never associated virginity with chastity and purity. The closest idea to the Western virgin was the otome (maiden) who was thought to be lacking sexual desire in addition to experience. The Western ideas of virginity in relationship to marriage – that is, a woman should remain virgin for her husband – didn’t appear until the 19th century (McLelland, 2010). This isn’t to say it was okay for women to have sex. During the Tokugawa Period, both men and women could be considered adulterers. Married women, unlike men, were penalized. Women were property of husbands or fathers. Adultery was a property dispute that was left to the decision of those involved. Punishment could be everything from a fine to death"
So in recent history it has become a part of their culture that sex should be something that happens after a long relationship and often until marriage has happened, so.... while I'm not saying those 17% are all holding out for their true love, there is a chance that some % of that could be, but also a chance that a % of them answered the survey in a way which they felt their culture is more expecting them to, that is to say they're a virgin since they're unmarried since it's a loaded question with a stigma over it.
edit - Out of interest based on the final line of your post, do you not consider homosexuals to be capable of having sex? I'm not sure I understand what you were getting it?