In Japan, Fortresses have been built since early times. In the 15th century, a particular need for castles arose after the central government's authority had weakened and Japan had fallen into the chaotic era of warring states (Sengoku jidai). Japan consisted of dozens of small independent states during the era that fought each other and built small castles on top of mountains for defense purposes.

With multiple rings of defense, the typical castle consisted of the so-called honmaru ("main circle") in the center followed by the ninomaru ("second circle") and sannomaru ("third circle"). In the honmaru, the castle tower stood, while the lords usually lived at a more comfortable residence in the ninomaru. as their uses were almost identical: defense, strategic control, impressing people who might cause trouble, the center of government, and al residence for feudal lords and their families. Their evolution parallels that of western castles.

Castles were still constructed primarily of wood, and many have been destroyed over the years, though they were built to last and used more stone in their construction than most Japanese buildings. There are more than one hundred castles extant, or partially extant, today, in Japan, out of around five thousand that once existed. For centuries fortresses were also built to serve as centers of governance, though castles continued to be built with these considerations in mind. They had come to serve as the homes of daimyo (feudal lords) and served to impress and intimidate rivals not only with their defenses but with their size and elegant interiors, architecture, and decoration by the Sengoku period.

Basic defensive fortifications were built on higher ground, from around the seventh century. Until the Warring States period (1467–1568), Japan's main castle-building era did not arrive. During this time, National treasures like the tenshukaku at Himeji, Hikone, and Matsumoto Castles were built. Usually, the lord of the castle lived at the foot of the hill, relocating to the main fort above when enemies approached. Around the area to form a castle town Merchants gathered, but there were no walls around the whole settlement, as often seen in Europe. Near their castles, some daimyō built gardens, including the famous Kenrokuen in Kanazawa and Kōrakuen in Okayama.

Japan's castles developed over the centuries from yamajiro or "mountain castles," through hirayamajiro castles built on hills surrounded by plains to hirajiro, "flatland castles", as the role changed.