
There’s one level in this underground dungeon that can only be seen, but not accessed, by the public.
“There’s something that’s been bothering me on my commute, so could you please look into it?”
That was the message our Japanese team received from a reader recently, and it immediately piqued our interest. The message went on to reveal that at Korakuen Station in Tokyo, on the way from the Marunouchi Line to the Namboku Line, there’s an elevator with a button for a floor labelled as “B3”. Due to the setup of the station platforms, however, the floor doesn’t seem to make sense, but with the reader feeling too timid to press the button, they asked our team of reporters to investigate.
▼ So we headed out to Korakuen Station to visit the mystery floor.
After arriving, we walked along the Marunouchi Line platform, where we noticed a wall mural that resembled a castle from Dragon Quest. This seemed like an apt artwork for our adventure, but it also made us fear that difficulties and dangers might lie ahead.
Japanese train stations are so vast they’re often referred to as dungeons, and this mural seemed to be challenging us to push through to the final stage, defeat the boss, and rescue the princess.
▼ Feeling emboldened, we scanned the signboard and headed to the elevator.
▼ It didn’t take us long to reach the lift, which looked like any other ordinary elevator.
The Marunouchi Line is located on two above-ground floors, while the Namboku Line is located on six underground floors. With a difference in elevation of approximately 41 metres (134 feet), these are two of the largest subway lines in Tokyo.
Stepping into the elevator on the B1 level, we looked at the control panel, where we saw buttons for B1, marked “改札階” (“Ticket Gate Floor”), B5 (“都営線連絡階” [“Toei Subway Connecting Floor”]) and B6 (“ホーム階” [“Platform Floor”]). This was the same as the floor listing on the sign posted outside the lift when he got in, but inside, there was also an unmentioned “B3” level, which unlike the other levels, had no explanation next to it.
Finger quivering, we reached out to press the B3 button. However, after pressing it, it refused to light up, and what’s more, it triggered an announcement, with a calm-sounding pre-recorded voice saying: “No stopping on that floor”.
With other passengers in the elevator, the announcement hung in the air, creating an awkward moment. We could feel everyone’s eyes on our back, as if they were wondering why we’d pressed the button, but our embarrassment was soon forgotten as the lift began its descent.
▼ Camera poised to capture images of the mystery floor, we shot this video of the B3 level.
As indicated by the announcement, the elevator didn’t stop on this floor, and from what we could see of it, it didn’t appear to be intended for public use. Although it was brightly lit, there was no sign of life there, making it seem like a foreboding area in a zombie game, where the undead might burst through the door at any moment.
Looking closer at the sign on the door reveals the reason for its existence, as we could make out the words “変電設備” (“Electrical Substation Equipment“). Substations are facilities that convert high-voltage electricity sent from the power company into a voltage that can be used at stations and on trains, so the B3 level appears to be dedicated to equipment that supports the underground workings of the station. Stations consume a huge amount of electricity, running the subway, operating the lights and escalators…and the beating heart of it all is housed on the mystery B3 floor.
While ordinary members of the public aren’t able to access this level, it does need to be accessed by maintenance workers, who likely have a way of bypassing the normal controls, either through a special key, code or prior permission from station staff, hence the existence of the B3 button.
Being able to see, but not access, the floor does give it a mysterious allure for people using this lift. It’s just one of the many mysteries you’ll find inside Japanese train stations, like the secret stairs at Tokyo Station.
Photos ©SoraNews24
● Want to hear about SoraNews24’s latest articles as soon as they’re published? Follow us on Facebook and Twitter!
[ Read in Japanese ]










Tokyo station becomes first in the city to install an inclined elevator
The golden escalator hidden at a Tokyo train station
What are these strange empty “seats” that are being spotted in Tokyo train stations?
The cool secret hidden in Tokyo Metro pillars at Ginza station
Secret stairs at Tokyo Station dungeon come with a serious warning
Ohaw? Ruibe? Pocche? While traveling in Japan’s north, we try Ainu cuisine for the first time
Narita Airport Transit & Stay Program returns after six years with free tours and festival experiences
Japan’s double-decker portable rice cooker/bento maker is better than ever with new version
Wait, some Shinkansen trains already have private booths that only cost 1,500 yen for an hour?
We recommend not buying one pack of Japan’s new convenience store corn soup-flavor fried chicken
Sushi Bus: Japan’s first conveyor-belt bus lets you eat sushi while sightseeing around Tokyo
Anime fans can now wear a Seiko watch inspired by Japan’s One Piece Shinkansen
Studio Ghibli unveils new interactive stationery dioramas that bring anime movies to life on your desk
German woman rescued from Mt. Fuji after suffering altitude sickness symptoms, hiking to peak anyway
The Japanese government is ending its Cool Japan Fund program
12-year-old British girl who went missing in Tokyo found safe after visiting anime sites around Yokohama
7-year-old boy left behind on Mt. Fuji by his own dad
Studio Ghibli composer Jo Hisaishi just set three Guinness Records
Japan’s Rabbit Island in danger of becoming Boar Island, tourists asked to follow feeding rules
7-Eleven Japan brings back best-selling flat croissant that became a hit on social media
Stay at a hotel with a bed for your plushie in Japan
Foreign hiker on Mt. Fuji loses consciousness and dies, becoming climbing season’s second fatality
Tokyo subway installing new ticket gates that don’t accept payment through Suica or other IC cards
Air-conditioned dress shirts arrive in Japan to save working professionals from sweltering heat
Pokémon Center Online designates first Pokémon items that will require Japanese ID card to buy
Japanese toilet aims to attract foreign tourists but not everybody is happy about it
Tokyo’s newest viral dessert is like a Japanese parfait inside a bread bun [Taste test]
Japanese Shinkansen becomes an overnight hotel for three nights this summer
New Japanese vending machine at Shinkansen station sells cups of ice on platform
Japan announces sudden 400-percent increase in visa fees for foreigners entering the country
Japan’s human washing machines will go on sale to general public, demos to be held in Tokyo
Studio Ghibli has a new anime out, and there’s only one place in the world where you can see it
Starbucks Japan releases new drinkware and goods for Valentine’s Day
Starbucks Japan releases new sakura goods and drinkware for cherry blossom season 2026
Japan’s newest Shinkansen has no seats…or passengers [Video]
Japanese ninja certification exam attracts 131 candidates from Japan and abroad
Salomon releases Japan-exclusive Mt. Fuji hiking gear that doubles as an amazing souvenir
Put sesame oil in your coffee? Japanese maker says it’s the best way to start your day【Taste test】
Tokyo gets its first subway station ramen vending machine
Act of Japanese kindness touches one man’s heart, provides hope for elevator etiquette
Japanese pizza chain opens stand at Tokyo station platform
Secret staff cafeteria at this Japanese train station is still open…for those in the know
How to cancel a floor on a Japanese elevator
Fossil of an extinct crab discovered in a pillar at Tokyo Station
Tokyo Station’s second-most popular bento is great because of what it isn’t【Taste test】
The Japanese train station famous for mysterious dancing cats
What to do if your phone battery dies when using a mobile transit pass on a Japanese train
Downtown Tokyo set to open its most important train station in 50 years, and now it has a name
Doai Station: The deepest station in Japan is also one of the scariest, like a video game dungeon
Tokyo Station Waterscape Toilet looks more like an aquarium than a bathroom
Japanese electronics store cleverly disguises its elevator to make it look exactly like a train
There’s a shrine and strange scene waiting for you at the top of this Japanese train station
What’s the real reason for the ‘floating’ 3-D signs at Haneda Airport?
Stay in a special Tokyo Metro train room at a hotel with a front seat to the railways