One Door, Two Locks Day (1-Door 2-Lock no Hi)

What is One Door, Two Locks Day?

January 26th is "One Door, Two Locks Day" in Japan. It was established by MIWA LOCK CO., LTD., based on a wordplay reading "1 (one), 2 (two), 6 (rock)" as "one-two-lock." The day promotes the practice of "one door, two locks"—installing two locks on a single door—to raise security awareness in homes and offices. January is also a time when break-ins tend to increase, making it an excellent opportunity to review your security measures.

The importance of one door, two locks

Most burglars dislike spending time picking locks. According to data from the Tokyo Metropolitan Police Department, about 70% of burglars give up if breaking in takes more than 5 minutes, and almost all give up if it takes more than 10 minutes. Adding a second lock not only increases physical security but also creates a visual deterrent—signaling "this home takes security seriously"—which can be a powerful psychological barrier.

Evolving lock-picking countermeasures

"Lock picking," a technique for tampering with keyholes, used to be widespread, but more complex structures like dimple keys have since become common, making picking much harder. However, methods like "thumb-turn manipulation" and forced entry with crowbars have become more sophisticated in recent years. One door, two locks remains one of the simplest and most effective defenses against all of these intrusion methods.

The role and benefits of "auxiliary locks"

A lock added to a door that already has one is called an "auxiliary lock." These range from full installations requiring construction work to types that attach with adhesive tape or clamps, suitable even for rental properties. Installing auxiliary locks can dramatically improve security not just for front doors, but for windows too.

Don't forget about windows

In fact, windows are the most common entry point for burglars in detached houses. It's recommended to apply the "one window, two locks" approach as well, attaching auxiliary locks to the top and bottom of window sashes. Adding a second lock to the front door while also reviewing the locks on balconies and windows in blind spots contributes to the safety of the entire home.

Key points for effective crime prevention

• "One door, two locks" physically buys more time during a break-in attempt
• Choose products with the "CP mark" (a certification for crime-prevention building components)
• Use sensor lights at night—burglars tend to avoid "light"
• Make it a habit to lock all doors even for short outings, like taking out the trash
• Don't leave items around your home that could be used as footholds, such as ladders or trash cans

Updating your security awareness

Security measures aren't a one-time task. Regularly check whether locks have become loose with age, and if you have battery-powered electronic locks, check that the battery level is sufficient. It's also worth considering newer technology, such as smart locks that let you lock and unlock doors—and check their status—remotely via smartphone.

Community watch

The basics of crime prevention are "individual measures" and "community vigilance." Areas where neighbors regularly greet each other and pay attention to suspicious vehicles or people tend to be less attractive to burglars. One Door, Two Locks Day is also a good opportunity to think about building a safer community together.

Ideas for enjoying One Door, Two Locks Day

• Inspect the locks on your doors and windows, and lubricate them with the appropriate product if they're sticking
• Check out the latest auxiliary locks and security products at a home improvement store
• Hold a "security meeting" with your family to confirm communication methods and rules in case of an emergency
• Display a "CP mark" sticker to show that your home takes security seriously

The peace of mind that comes from security

One Door, Two Locks Day is a day to take a closer look at the "keys" that protect your loved ones and belongings. A little extra effort and preparation can create great peace of mind. Don't assume "my home is fine"—on January 26th, why not double-check your home's security and aim for days filled with calm peace of mind?