Founded in 1519, this was the home and center of power for three generations of the Takeda (Nobutora, Shingen, and Katsuyori). The Takeda reached their pinnacle under Shingen who actually participated in a revolution that overthrew his father and sent him into exile when he found out that Nobutora was going to make Shingen's brother Nobushige his heir. Shingen is made famous in an old poem that claims "men are your castle, men are your castle walls, men are your moats." This relates the emphasis that Shingen put in his people and during his rein he didn't build any castles beyond the fortification at Tsutsujigasaki.

The picture above is taken from the corner of Nishi Kuruwa (west bailey) looking across the moat of the main compound.

You'll notice this isn't called a castle here. It's not called a castle in Japanese either. It's really just a huge heavily fortified mansion or estate. For the time period in which it was originally built it would have surely been an impressive structure.