Yesterday, Tokyo hosted the Rainbow Pride Parade – the city’s annual celebration of LGBT people and sexual minorities in Japan, now in its fifth year. The parade is the culmination of a week of Pride-related events, political, social and artistic, and is accompanied by a two-day festival at Yoyogi Park.

The speed with which Rainbow Pride has grown in the past five years is astonishing, and it continues to accelerate. When I first attended four years ago, Pride was a huddle of small booths that barely occupied half of the Yoyogi event space; now, it’s bursting at the seams, with more and more major companies, foreign embassies and retailers vying for space and attention. The parade itself is emblematic of the change; a few years ago, it was a small affair very heavily dominated by foreign faces, and many of the Japanese participants wore sunglasses and face masks to avoid being recognised or pictured. Yesterday, five thousand people marched through Shibuya and Harajuku – the vast majority of them Japanese. Five thousand appears to have been a limit set by some agreement with the authorities, because the numbers could easily have been higher; on Sunday morning, people were being turned away from signing up to march, as the parade was full.

It took almost two hours, standing in the hot sunshine, to see the whole parade pass by on its way back into Yoyogi Park – the marchers being applauded and high-fived by the spectators lining the path as they returned. There were no masks and sunglasses. There were foreigners, of course, but hugely outnumbered by local participants. There were families with children. Large groups of staff from major companies, including family brands like Johnson & Johnson, big banks and financial firms, and tech companies like Google and Netflix, all marched wearing company T-shirts and banners proclaiming the companies’ support for Pride.

None of this would be remarkable in many cities around the world, of course, and Tokyo Rainbow Pride is still a minor affair compared to Asia’s largest Pride event, in Taipei, let alone the huge Pride events in US and European cities. What is truly remarkable, though, is the speed of the growth and the rapid, yet almost unnoticed, change from a culture of anonymity and reluctant activism to genuine, open, “pride”.

In this, Rainbow Pride is merely a useful barometer of deeper, more important changes that are occurring within the fabric of Japanese society itself. More and more universities now have thriving LGBT circles – incidentally, my own university, Waseda, has what I believe is Japan’s oldest student LGBT society, GLOW – and several of them were represented at the Pride Festival, including one from the country’s most prestigious school, Tokyo University. There has been a slow but steady stream of Japanese companies stepping forward to say that they will offer the same benefits to LGBT staff and customers that they do to straight people. Several Japanese political parties now include references to LGBT rights in their manifestoes; the ruling LDP is not among them, but the party’s policy chief, Inada Tomomi, made an official visit to Rainbow Pride on Saturday, becoming the most senior Japanese politician to do so. (While Pride is a fun party, it’s also a serious political event; the address after the end of the parade yesterday was given by US ambassador Caroline Kennedy, who was joined on stage by the British and Irish ambassadors.)

Inada’s public support for Pride is a really interesting thing to think about in the context of the future of LGBT rights in Japan. That’s partially because Inada remains a rising star in the LDP, and many consider her to be a future Prime Minister – a role for which current Prime Minister Abe Shinzo appears to be grooming her. More notable, though, is that Inada is, in general, an ultra-conservative figure. She is a hardline historical revisionist who disputes the accepted history regarding the Rape of Nanjing and WW2 comfort women; she approves of the remilitarisation of Japan, makes regular official visits to the controversial Yasukuni Shrine and is, like many of her senior LDP peers, a member of the hard-right Nippon Kaigi organisation. You would fully expect someone with this background to be deeply conservative on the issue of LGBT rights; the experience of Western countries has been that conservative nationalists are generally extremely anti-LGBT in their stances. Yet Inada was right there at Rainbow Pride, and directly stated her support for human rights and diversity.

This highlights the key difference between Japan and western countries on the issue of LGBT rights; Japan is not, and has never been, a Christian country. It has no religious problem with homosexuality, though it has imported some negative attitudes from the west – prior to the Meiji Restoration in the late 1800s, at least among the upper classes, homosexuality was seen as an indulgent vice, at worst; even The Tale of Genji, written over a thousand years ago, reveals the eponymous prince’s bisexuality in an entirely matter-of-fact way. Human Rights Watch noted last week that homophobic bullying is a problem in schools, and that many teachers are ignorant of, or actively contributing to, the problem; but by and large, LGBT rights is not a hill that Japanese conservatives are willing to die on. Honestly, most of them don’t really care about it, or know very little about it; unlike conservatives in Western countries, those in Japan are, for the most part, generally disinterested in this whole field, and certainly not prepared to expend significant time or energy in fighting against change or progress.

That’s important, because Japan is at a tipping point for LGBT people. Five thousand smiling, waving people, their faces uncovered, marching through Shibuya’s scramble crossing and down a packed Omotesando on a Sunday afternoon is just the tip of the iceberg. There is a line in Japan’s demographic chart; above it, most LGBT people are in the closet, living double lives and keeping their sexuality, for all intents and purposes, invisible. Below the line, you have LGBT young people who, increasingly commonly, come out to their family, their friends, their classmates and even, sometimes, their employers. Hard data on this is impossible to source, but anecdotally, the proportion of LGBT people in their 20s who live openly is an order of magnitude higher than for those in their 40s. Each year, that demographic line rises up the chart, and more and more young people choose to come out.

That tipping point will be familiar to anyone who knows the history of LGBT rights in the west. It’s the point where coming out of the closet becomes the rule rather than the exception; where coming out becomes a rite of passage for young LGBT people, rather than a rare and often forced event some of them have to endure. It’s the point where society has to confront and seriously think about its attitudes to LGBT people and their needs, because they’re no longer an abstract – strange people who do peculiar things and dress oddly and sometimes make funny jokes on TV – but a concrete living reality; your son or daughter, your brother or sister, your cousin, your best friend, your neighbour, your colleague. The single most powerful weapon in the fight for LGBT rights is actually opening ordinary people’s eyes to the LGBT people around them, among their friends and loved ones. Reaching that point is slow, but once it’s reached, change happens very quickly; “gradually, then suddenly”, as Hemingway would have it.

In the West, that sudden burst of change was opposed bitterly by entrenched conservatives; in Japan, though, there’s no interest or appetite for that fight from the conservative camp. There are plenty of old men in political positions who are utterly ignorant of LGBT issues and say stupid, bigoted things – the world won’t run out of those any time soon – but the prospects for any organised conservative resistance to progress on LGBT rights, once that progress becomes a populist position, are very slim. Once Japan advances beyond the tipping point, change will happen very quickly indeed, and with minimal friction.

Viewed in this light, even the high instance of homophobic bullying in schools can be seen as growing pains; homophobia in schools has risen precisely because it is increasingly common for LGBT students to be open about their identities. This is enormously brave, and it’s heart-rending to hear of them being bullied or taunted for it; but they are of a generation who can’t imagine hiding their sexuality, who would prefer to be bullied than to lie to the world about themselves, and as a result they’re a generation that is going to change Japan profoundly.