Although the slender hinoki cypress is an evergreen tree, it will lose some of its leaves. In fact, this is the case for several types of popular evergreens. In the fall, these species may drop a few of their oldest leaves. Every few years, they may drop a larger quantity of leaves, which is alright as well. However, if the leaves of your tree are showing significant discoloration and dropping in excess, you may need to consider your tree's health.