Bicycles are as much a part of Japan as samurai and Pocky. In a country where cars and their associated costs are expensive and public transportation only goes so many places, bicycles are an affordable means of faster-than-walking transportation. They’re ubiquitous to the point that people are allowed to ride their bikes on the sidewalk, and pedestrians will unconsciously move aside if they hear a bicycle bell. That’s not the only difference, though.
Bicycle parking lots aren’t something restricted to Japan, but since free parking in Japan is just about nonexistent, they’re pretty common. The fees are much cheaper, of course, and you can fit a lot more in the same space. In Nagoya, they have bike stands along some sidewalks, while near my home station, there’s a sizable lot in front of a Tsutaya. I have found places where people park for free, though, even when they technically shouldn’t be able to. In Kamata, for example, there’s a long stretch of sidewalk with signs expressly forbidding bicycle parking — surrounded by rows of bikes. I imagine they don’t get impounded simply due to volume; while impounding one or two or even five bikes would be plausible, thirty would be seen as spiteful (whether or not those thirty were legally parked).
In my experience, cyclists act like either vehicles or pedestrians, whichever benefits them most in a given situation. They will ride on the street when it suits them, but think nothing of running red lights and red crossing signals. I’ve had cyclists ride past me so close they banged my arm hard enough to hurt, seen them dart through a crowd of people with barely room for error, and watched them ride the wrong way on a one-way street. Many crosswalks have a narrow strip painted just for bike traffic, yet I rarely see bicyclists use them. In some places, wide sidewalks have spacious bike lanes painted along the side, but people still ride wherever they like. The most baffling is that one would expect them to ride on the left, since that’s the side of the road cars and trucks use here — and the side bicycles would have to take when using the street — but that’s generally not the case. When not on a major street, cyclists ride on the left, right, or center, sometimes two abreast (which, on a narrow road or sidewalk, makes it a close shave when they encounter a pedestrian).
Finally, it’s important to note that cyclists will sometimes stop their bikes right in front of you without warning, so good reflexes will come in handy — and even then it’s not always enough, as I’ve learned the hard way once or twice. It’s definitely not what I’m used to.