The secondary armament consisted of a dozen Elswick Ordnance Company "Pattern Z" quick-firing (QF), 40-caliber, 6-inch guns. Only four of these guns were not mounted in armored casemates on the main and upper decks, and their mounts on the upper deck were protected by gun shields. Their AP shells were fired at a muzzle velocity of . The guns were provided with 150 rounds each. "Yakumo" was also equipped with a dozen 40-caliber QF 12-pounder 12-cwt guns and eight QF 2.5-pounder Yamauchi guns as close-range defense against torpedo boats. The former gun fired , projectiles at a muzzle velocity of .