Hamamatsu Information Book

Matsudaira Nobuyasu, originally named Taketichiyo, was born in March 6 (or 7), 1559 in Sunpu (present Shizuoka City). He was the first son of Tokugawas Ieyasu. His mother, Tsukiyama Gozen, was Ieyasu's official wife and Imagawa Yoshimoto's niece. At the age of five, Nobuyasu engaged with Oda Nobunaga's daughter, Tokuhime. His genpuku, coming of age celebration, was held in the Hamamatsu castle with a nogaku play in 1570. 
 

Young Nobuyasu successfully involved in various battles with his father as the lord of Okazaki castle. Mikawa Monogatary Toshogu-go Jikki (the True Record of Tokugawa Ieyasu) notes that Takeda Katsuyori, who lost against the Tokugawa in the Battle of Nagashino, commented on Nobuyasu's well performed lead of his army, saying Nobuyasu would be a huge threat in the future. Mikawa Monogatari (the story of Mikawa region) depicts him as a valiant man who was filial to Ieyasu. It says there wouldn't be a young man as brilliant as Nobuyasu.

 

However, his hopeful life took a sudden turn in 1579 when his wife sent a letter to her father, Nobunaga, claiming that Nobuyasu and his mother was secretly communicating with the Takeda. This angered Nobunaga. He demanded Ieyasu for Nobuyasu's seppuku (suicide). Ieyasu had to agree to keep the Tokugawa clan from destruction. Ieyasu told Nobuyasu Nobunaga's wish on August 3. He was transferred to the Horie castle on August 9, and then to the Futamata castle. He committed seppuku in the castle on September 9.

 

Tenryu-shi-shi (History of Tenryu City)

Hamamatsu-shi-shi (History of Hamamatsu City)

Nobuyasu to Futamata-jo (Nobuyasu and Futamata Castle)