Prior to the Battle of Sekigahara, Ishida Mitsunari planned to capture Chiyo's mother-in-law Hosokawa Gracia as a hostage.

When the Western army approached Gracia's mansion, she asked her servant to kill her and set her residence on fire.

Gracia's death caused much chaos, and damaged Ishida Mitsunari's reputation, which ultimately led to his defeat at the Battle of Sekigahara.

After her marriage, she did not bear a child with Nagatsugu but adopted Nagamitsu (later called Nagaie, the fourth son of Oda Nagataka).

Many letters remain that were written by Matsu to Chiyo kept at the Tamagawa Municipal Library in Kanazawa and the Museum of the Maeda Tosa-no-kami Family.