How a Terrible Japanese Porn Franchise Became the World's Longest-Running Film Series

Tokyo Weekender

16-06-2025

There's a lot to be said about Japan's porn industry.
It's huge
, earning tens of billions of dollars a year. It
helped keep people indoors
during the height of the COVID-19 pandemic. And it even has its own
porn actress theme park
. It
pushes the envelope
on the definition of porn.
The world of Japanese adult entertainment also has another claim to fame: the creation of the (likely) longest-running film series on the planet. However, it's really more of a claim to infamy, as it belongs to the
Groper Train
(Japanese title:
Chikan Densha
) movies.
List of Contents:
Defining the Longest-Running Film Series
A Dark Journey Into the Films
The Destructive Reality Behind Groper Train
Final Stop for Groper Train
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Still from 'Chikan Densha: Ikenai Yume Ryoko' (2014) | IMDB
Defining the Longest-Running Film Series
How, exactly, do you define the world's 'longest-running' film series? If you're going by which series debuted first, then Universal's
The Mummy
— kicking off in 1932 and last in cinemas in 2017 before going on hiatus — is due the title. You could also make a case for Batman
,
since his first serial came out in 1943, and we're still getting new movies about the Dark Knight. Those, however, would be the
oldest
franchises.
If you measure the longest series by the number of entries it produced, some sites will tell you that the title should go to the
Wong Fei-Hung
filmography about the titular Chinese martial artist and folk hero who's been portrayed by Jackie Chan, Jet Li, Sammo Hung and other actors who starred in 123 movies.
However, 123 is just a little over half of the number of entries in the
Groper Train
movies. The exact number is actually a matter of some discussion, as a lot of the
Groper Train
films — and information on them — have been lost. Online sources put their total number at 227 films.
The films in the series were written and directed by dozens of different people and were primarily distributed by Xces Film, Okura and Shintoho, according to the documentary
Riding the Groper Train — Part Two
. And if that last studio name sounds familiar, it's because it is related — in a roundabout way — to Toho, which is best known as the producer and distributor of
Godzilla
,
Akira Kurosawa movies
and Studio Ghibli productions.
Still from 'Chikan Saishu Densha' (1978) | IMDB
A Dark Journey Into the Films
The
Groper Train
films primarily and sort of self-explanatorily take place on trains where a woman — and also a man in one gay take on the theme — gets molested by a groper. You'd think that such a concept might wear thin after a few dozen movies, but the
Groper Train
series has been around since 1975.
The films in the series are all fictional, featuring adult film actors — although some of the earliest entries were shot guerilla-style on real trains. Many of the early films that were shot on a set still featured exterior scenes on actual station platforms as well.
Stylistically, the
Groper Train
series is a classic pink film. Japanese pink films, or
pinku eiga
, emerged in the 1960s as erotic, low-budget independent films that blended soft-core porn with stronger narratives, artistic styles and experimental storytelling. To qualify as a pink film, a work generally had to include a minimum number of sex scenes, though Japanese censorship laws prohibited the depiction of actual intercourse or genitalia.
During their peak, pink films were controversial, yet tolerated as training grounds for emerging talent. For instance, director Takahisa Zeze — the force behind acclaimed films like
Tapestry
,
one of the best Japanese movies of 2020
, and
Tonbi
, a
poignant film with a focus on single fatherhood
— was once part of a group called the 'Four Heavenly Kings of Pink.'
Obviously, none of the
Groper Train
films rise to those levels of filmmaking, but the point is that they weren't just porn without a story. They had actual plots — some of the films were framed as detective thrillers, for instance, and at least one involved time travel — and that allowed them to stick around and eventually break filmmaking records.
Still from 'Chikan densha: Chibusa ga Yureru' (1990) | IMDB
The Destructive Reality Behind
Groper Train
The reality behind
Groper Train
is sobering. Sexual assault on Japanese trains is a pervasive problem, so well-known around the world that the governments of Canada and the UK are
warning tourists about it
. Even the Japanese word
chikan
— meaning molester, groper or simply pervert — has started to appear in international travel advisories. Most victims, though, remain Japanese.
A 2024
government survey
found that 56.3% of women and 15.2% of men had experienced groping on trains, with up to 3,000 attacks occurring per year. And that's just the reported cases. It's alleged that most attacks happen in the morning when the trains are packed, meaning that many of the victims are minors on their way to school.
Nearly 40% of victims don't engage the groper out of fear and end up traumatized by the assault, suffering from physical and mental distress, flashbacks and agoraphobia. Studies have shown that the best way to stop a groper is to get the people around you to intervene. There are some apps that help with that, with one of them, Digi Police, downloaded 800,000 times between its release in 2016 and April 2024.
The only real long-term solution to groping is other passengers stepping up to help. A study has shown that 96.8% of gropers stop when they're called out by a third party, because train perverts are cowards who prey on the vulnerable.
Final Stop for Groper Train
In the documentary
Riding the Groper Train – Part Two
, pink director and actor Yutaka Ikejima said that Japan used to release up to three
Groper Train
movies each for cinema's three peak seasons, i.e., during the New Year period, Golden Week and the summer.
And different studios were free to make their own films under the
Groper Train
umbrella — resulting in dozens of new films per year.
In 1986 alone, that meant 17 new
Groper Train
releases. However, since then, the numbers have steadily fallen, and the franchise now seems to be dead. The last installment came out in 2020, with only one movie released in 2019, none in 2018 and two in 2017. Maybe now's the time for
The Mummy
to emerge from hiatus and reclaim the crown.
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