Wakuya Castle, Japanese castle in Wakuya, Japan.

Wakuya Castle is a flatland-mountain castle (hirayamajiro) on a 20-meter tongue of land in Wakuya, Miyagi Prefecture, with the Eai River flowing about 5 meters below to the west and south. The grounds retain earthen ramparts and dry moats, and a surviving corner turret (taiko-dō) stands on the site; beside it is a three-story keep-like building that serves as a museum but is a faux keep, not a reconstruction of an original tower.

Wakuya Castle was first held by the Wakuya clan, retainers of the Osaki, and passed through the Kimura before becoming the residence of the Watari, Date retainers. The second and third lords, Shigemune and Sadamune, developed the fortifications, and Sadamune was permitted to take the Date name, founding the Wakuya-Date line. His successor Muneshige was killed in the Date Disturbance after a dispute with Munasuke Harada.

The castle grounds are now Shiroyama Park, known for cherry blossoms in spring. The name Wakuya comes from the Wakuya clan, who held the site before the Date. The existing corner turret, called Taiko-do, is the only surviving castle structure in Miyagi Prefecture; the three-tier keep-like building beside it is a modern museum, not a reconstruction of a real keep.

The site is within walking distance of Wakuya's town center, and signs along the path help visitors find their way through the grounds. Sturdy footwear is a good idea, as the earthen mounds are uneven and paths tend to get muddy after rain.

The castle's defenses relied almost entirely on the river and the natural shape of the land, with very little stone construction involved. This approach was common in the region but makes the ruins harder to read than a stone castle, since much of what remains simply looks like raised ground.