Hosen-in's "blood ceiling" traces back to the 1600 Siege of Fushimi Castle. Torii Mototada and other Tokugawa loyalists took their own lives when the castle fell to the Western Army under Ishida Mitsunari, and the bloodstained floorboards were later installed as the temple's ceiling. There is no record of Mitsunari himself visiting the temple, but it still conveys the tragedy of this Sekigahara prelude.

In July 1600, Torii Mototada defended Fushimi Castle with around 1,800 men against a Western Army of approximately 40,000 led by Ishida Mitsunari. After ten days of fierce fighting the castle fell and Mototada took his own life. The bloodstained floorboards were later transferred to Hosen-in as a blood ceiling, where they still commemorate the spirits of Mototada and over 260 others. As a symbol of 'friendship staked on death' with Ieyasu, this blood ceiling continues to move all who see it.