Growing and tending little trees in containers is called bonsai in Japan. Bonsai translates to "planted in a container" from its original Japanese. Bonsai trees are small versions of full-sized trees that are grown to look like their full-grown counterparts.
Bonsai is the art of shaping and pruning a tree to create a tiny representation of a larger tree while maintaining its natural appearance. Small pots are used for growing the trees, and they need constant care, including watering, fertilizing, and repotting.
Many bonsai aficionados devote decades to honing their skills and developing increasingly complex bonsai sculptures. There are bonsai aficionados all over the world; the art form is not unique to Japan.