If you’ve ever strolled through a quiet Japanese neighborhood, you might have noticed something unusual—clear plastic water bottles neatly lined up along fences, walls, or the edges of gardens. At first glance, they might look like litter or forgotten leftovers from a picnic. But in reality, these bottles are placed there on purpose. They’re known as nekoyoke, which translates to “cat deterrents.”

Japan is famously fond of cats. They’re celebrated in folklore, pop culture, and even daily life. Yet, stray cats can also be a challenge, especially in residential areas. They may dig up gardens, scratch property, or leave behind waste, which raises concerns about cleanliness and the spread of disease. To combat these issues without harming the animals, some residents turn to a simple solution: placing water bottles outside their homes to keep the cats away.

The idea behind nekoyoke is that light reflecting through the water inside the bottles creates flashes or distortions that confuse or scare cats. Some believe the shifting reflections from sunlight or streetlights disturb a cat’s depth perception, making them cautious about approaching. Others think the shimmering effect simply startles them enough to move along. To many outsiders, it seems odd. But in Japan, it has become a recognizable sight across cities and suburbs.

What’s fascinating is that this practice didn’t actually begin in Japan. It’s thought to have originated in the West during the 1980s, where people first used water bottles to deter dogs from wandering into yards. Over time, the method found its way to Japan and was adapted for cats, which tend to be more common as urban strays.

But does it really work? According to animal behavior experts, the answer is no. There’s no scientific evidence proving that water bottles are an effective deterrent for cats. Most cats will ignore them completely, especially at night when reflections are minimal. Still, the tradition persists. For many, it’s less about proven results and more about the hope that it might work—or simply because it has become habit.

Even without scientific backing, the practice is harmless. The bottles don’t injure the animals, and they don’t require much effort to put in place. Over time, nekoyoke has taken on a role that’s less about pest control and more about cultural expression. To visitors, it’s a quirky and memorable detail of Japanese life, a blend of creativity and subtle problem-solving that reflects broader values in the culture.

In fact, nekoyoke says a lot about the Japanese way of addressing problems. Instead of resorting to traps or chemicals, people opt for a harmless and peaceful solution. Whether or not it’s effective doesn’t matter as much as the intent: protecting their space while avoiding conflict with nature. For many residents, it’s also a matter of keeping up appearances. A row of bottles may serve as a quiet signal to neighbors that they’re taking steps to maintain cleanliness and order in the community.

So, while the effectiveness of water bottles as cat deterrents remains questionable, their presence tells a bigger story. They’re a small but fascinating example of how traditions—whether practical or not—become woven into daily life. For travelers and curious onlookers, the bottles add a touch of mystery and charm to Japan’s streets, standing as a cultural curiosity that continues to puzzle and intrigue.