Original: Later in 1638, the grandson of Tokugawa Ieyasu, Matsudaira Naomasa enters the castle since the Horio clan had no heir, and his family ruled until the abolition of the han system.
Simplified: Later in 1638, the grandson of Tokugawa Ieyasu, Matsudaira Naomasa entered the castle because the Horio clan had no heir. Matsudaira's family ruled until the end of the han system.