At Kouza Shibuya, there is a small Japanese temple named Jousenji （常泉寺） with an absolutely beautiful Japanese garden. If you love flowers and different types of plants, this is the place to go. The gorgeous flowers change seasonally and the garden is copious with different colors each season. I went during the spring, right when I was doing hanami (cherry blossom viewing). At that time, the most memorable plants was the drooping Sakura tree. The garden makes you feel as though you are in a totally different world.
The temple is also famous for love and studies. If you want to improve your fortune in those areas (or any other), I recommend you to go here!
This park is also an excellent place to go if you want to avoid the crowds. Few Japanese even know about this area, so if you want some quiet time at a breathtaking Japanese garden, this is the place to go!