In 1600, when the battle of Sekigahara broke out, Sukenao was at the Osaka mansion of the Hosokawa clan, serving as the bodyguard to Gracia HOSOKAWA, Tadaoki's wife; when Gracia became embroiled in Mitsunari ISHIDA's hostage strategy and committed suicide, it is said that Sukenao was aided by his gunnery pupils and managed to flee the mansion.
1600年、関ヶ原の戦いが起こったときは、細川氏の大阪屋敷にいて、忠興の妻である細川ガラシャの警護をしていたが、ガラシャが石田三成の人質作戦に巻き込まれて自殺すると、自身は砲術の弟子に助けられて屋敷から逃亡したという。