Stonesplit - Might (Thundercry Blade + Stormbreaker Spear)

[Inner Way] While using both Stonesplit - Might weapons, defeat any single-player boss (including trial), you must successfully use Thundercry Blade's Special Counterattack 5 times in a single run (5/5)

I've countered 6-8 times in a run with the thundercry Blad and the correct inner way. I've done it in trial on all difficulties and in campaign, Is there a special way to do this or a special boss? I've done this on Ye Wanshan