As with all landscapes and gardens that follow a theme, the plants and decor you choose play a major role in creating the atmosphere. This Japanese garden pond for example, even though it's a smaller element or "room" of a much larger garden, gets its Japanese element because of the type of flowers, other plantings, and decor that surround it.
The rest of the landscape could be of one or many other design styles or themes but walking into this area of the garden might make you feel like you've taken a trip to Japan or some other Asian country. Of course, that's just an example as most landscaping themes, yards, and plantings will generally follow the same style throughout the entire design.
For the most part, the plants, trees, and flowers in and around this pond are fairly general and would work in most gardens and landscapes. However, it's the decor that creates most of the Japanese atmosphere here. At the same time, there are a lot of different plants specific to Japan such as Black Pine and Maples that would help create an obvious theme even without the decor.