Carex are not true grasses
They are a genus in the Family Cyperaceae and are more commonly known as sedges. They are an undemanding evergreen, perennial ornamental grass that forms low hummocks of striking grass-like, colourful foliage that is often brightly hued or variegated.
For traditional Japanese gardens the low growing varieties such as Evergold are very suited alongside other plants such as Liriope. In mid to late spring many bear brown flower spikes on long stems. These grass-like plants are drought tolerant once established. Sedges are easy to grow and virtually maintenance free but combing through the plants in winter with your fingers to remove any tired or dead foliage will tidy them up.
Sedge plants produce tiny seeds which feed some birds, and many animals use the foliage as shelter. If you don’t want the plant to seed, cut off the seed heads in early spring.