From Glow Sticks to Wireless Penlights: How Japan's Concert Light Evolved, and Its Rules

A K-pop light stick ocean or a stadium full of phone flashlights will feel familiar. At a Japanese live show, fans hold penlights they control themselves, and some venues add wireless systems that change the color of every stick at once. The penlight is fan gear and part of the lighting design too, with the whole crowd as the fixture.

The light source has moved from flashlights to chemical light to battery-powered LEDs, and wireless control has joined the mix. This is the history of the penlight, the handheld light stick Japanese concertgoers wave to the music, told through both the technology and the venue rules.

The Short Answer: The Light Source Changed Three Times, and Each Time Who Chooses the Color Shifted

The penlight’s evolution was never a race for brightness. With each change of light source (bulb, chemical light, LED, wireless control), the party deciding the color changed too. First it was whoever brought the light. Next it was whoever bought it. Now it’s a transmitter in the venue. Rules like “27 cm maximum” are a by-product of that same shift.

The Lineage of Light: From Space Technology to the Fishing Pier to the Concert Hall

Chemical light is generally said to date from the 1960s, when it was invented in connection with the US Apollo program as a light source that could be used safely in space without fire or electricity. The long-established company that brought the technology to Japan is Lumica, founded in 1979 in Fukuoka Prefecture, on the southern island of Kyushu. It later carried the ampoule technology it had developed for night-fishing products into concert goods (J-Town Net’s interview with Lumica, in Japanese).

So the stick your neighbor snapped at the last show came from space exploration, by way of the fishing pier. The name “cyalume” itself comes from the trademark of the world’s first chemical light.

As for how Japanese concert audiences first started carrying lights, a widely told story says that in the mid-1970s a singer asked fans on the radio to bring flashlights. But this is an anecdote handed down within the industry, and the starting point in Japan remains hearsay. As with the arrival of pin badges in Japan, parts of this field’s timeline rest on oral tradition in the industry.

The biggest product advance is that a single stick can now switch between several colors. Choosing a color to match the member or the song has changed how fans pick what to carry.

What Happens Inside: Three Generations of Mechanisms

Each time the light source changed, the inside of the stick became something entirely different.

Generation 1: Chemical Lights (Disposable)

Two liquids sit inside, separated by a glass tube. Snap the tube and the liquids mix and give off chemical light. It needs no battery or power source, which also means you can’t adjust the brightness or change the color. Because it contains liquids, it can leak if it breaks.

Generation 2: Official LED Penlights (Reusable)

The grip holds batteries, LEDs and a button circuit that switches colors. The basic approach is to combine red, green and blue LEDs to make many colors, and each model keeps improving on the number of colors and how they render. Batteries vary by model: AA, AAA, button cells or rechargeable. When you replace a model, the old batteries often don’t fit.

Generation 3: Wireless-Controlled Penlights

This is the most interesting part technically. Take Sony’s FreFlow as an example. Sony’s FreFlow is known for using 920 MHz radio signals sent from the venue to control penlight colors; it now uses an app and Bluetooth. The signal is written in DMX, the lighting industry’s standard communication protocol, and goes out from a transmitter placed in the wings or near the lighting desk. Inside each penlight that receives it, a microcontroller drives an RGB LED, and tens of thousands of sticks change to the same color with no time lag (ITmedia PC USER, in Japanese). In dome-class venues, the huge covered stadiums that host Japan’s biggest tours, the antennas are spread around to reduce dead spots.

An earlier example of the same idea of lighting everyone at once is Xylobands, a wristband device from the UK. It has built-in LEDs and a wireless receiver, and its light is controlled from software. It was reported to have been distributed to visitors at the O2 Arena for a Coldplay performance in December 2011 (Silicon Labs). Japan’s wireless-controlled penlights can be seen as connecting that idea to the domestic culture of assigning member colors.

Beyond wireless, sound-synced models that analyze audio and light up automatically to the rhythm are also in practical use (Evixar, in Japanese). They aim to make synchronized effects possible even in small venues where installing a transmitter is difficult.

A Cultural Question: Who Decides the Color?

Alongside the technology, fan behavior at shows has changed too.

In groups built around oshi color, lighting your stick in your oshi’s color is basic etiquette. Some fans hold two sticks and split the colors between left and right, and there is a custom of switching everyone to white for signature songs and encores. Nobody set these rules. They are manners that built up over time at the genba, the live events where fans gather.

Even as wireless control has spread, some venues deliberately keep matching colors by hand. Interviews describe cases where staff and people nearby insist on calling out colors so the crowd matches (the ITmedia article above). A color that changes automatically is a unified look created by the production side. A color matched by hand is the result of choices made by the fans. It looks like the same moment of everyone turning the same color, but the meaning is entirely different.

The contrast with overseas is also clear. Official K-pop light sticks are made as dedicated merchandise, one design per group. In Japan, the mainstream approach is to reuse the same model across several groups and change only the color. Japan shares the vessel and separates by color; Korea separates the vessel itself. Neither is the right answer. The economics of merchandise are simply different.

As for how to wave them, fans are expected to avoid settings that are too bright, raising a stick above head height, and big swings with two sticks, because these block the view and endanger the people behind and beside you. A good guide is to keep your swing inside your shoulder width. In areas such as otagei, choreographed fan dance, the way you wave is itself a culture, but whether it’s allowed differs by venue.

Pre-Show Checklist

Just as manners differ from venue to venue, rules on what you can bring change from show to show. Here is what to confirm before you leave.

• Check the bring-in rules for each show on official channels. Length, number, brightness, whether flashing is allowed. Read the organizer’s notice, not secondhand social media posts
• Check battery type and count before you buy. They differ by model. Buying a replacement and finding your spare batteries don’t fit is a classic mistake
• Always carry spare batteries. From the merch line to the main show, your stick will be lit longer than you’d think
• Look up member colors in advance. Official announcements and show customs sometimes differ, so check both
• For a trip, check the airline’s rules. JAL has an FAQ (in Japanese) on carrying chemical lights (cyalume) onto the plane and checking them. Before an ensei, a trip to see your oshi, always confirm on the primary page
• Know whether your stick supports wireless control. A model without it can’t take part in automatic effects
• Decide whether to bring a spare. Venue-exclusive models sell out, so watch the advance announcements for venue-exclusive sales

What Happened Between Autumn 2025 and Autumn 2026

Four recent developments in the penlight world:

• December 2025: ITmedia ran a feature on wireless-controlled penlights. It went into the technology (infrared and 920 MHz radio) while reporting that the hand-matched-color tradition lives on alongside it (ITmedia PC USER, in Japanese). That a tech outlet covered the fan-culture side shows how mature the field has become
• September 2, 2026: Hololive Production officially announced its participation rules. The virtual YouTuber agency stated that concert lights longer than 27 cm may not be brought in (in Japanese). What matters in practice is that the length limit is a number in an official document. Standards differ by organizer
• September 2, 2026: TOHO animation STORE ONLINE announced plans to sell an automatically controlled penlight. It blinks to the sound, changes through 14 colors in total (in Japanese), and supports effects in which every light in the venue changes at once. That an official store of the film and anime company TOHO now lists an auto-control model as a regular product suggests the feature is no longer a special item
• The scale on the supply side. Ruifan Japan states on its website that it supplies more than 2 million products a year (in Japanese). That is one company’s figure, though. There are currently no statistics showing total shipments or market size for concert penlights across the industry. The penlight market reports published by market research firms include medical and industrial uses and are a separate category from cheering gear

The Oshi Lab’s Take: Where Did the Right to Choose the Color Go?

Read as a story about light sources, the history of the penlight is a technical history from chemistry to electricity. We find it more interesting as a shift in the right to decide the color. In the flashlight era, there was no color, only whether you had brought one. In the glow-stick era, color depended on how many sticks you bought. In the LED era, color became free at the press of a button. And in the wireless-control era, color comes down from the production booth.

The color that was supposed to be free has become the one you can choose least, under the most advanced technology. That isn’t decline. The beauty of a moment when everyone turns the same color can never be built from the sum of individual choices. But that beauty is an emotion prepared by the production side, a different thing from the act of choosing your oshi color and waving it. Shows that still match colors by hand probably exist because some people don’t want to give up the latter.

There are two implications for planners. First, if you introduce wireless control, leave time when people can choose colors manually. Fully automating a show removes the chance for fans to declare their own oshi. Second, publish bring-in rules with numbers up front. Hololive putting “27 cm” in an official document is a practical decision that cuts down on confiscations and arguments at the venue. Vague manners make the most conscientious people the most anxious. The rules for handling light shape the quality of the experience about as much as the light itself.

For consultations on live production and fan-gear design, contact KAZAORI Inc. (in Japanese). You can also try the Oshi Level Check (free diagnostic).

Related articles: What Is a Penlight? (Glossary) / What Is Oshi Color? / Venue-Exclusive and Early-Access Sales / Why Do Pin Badges Turn Into “Towers”?