Unlike Simple Domain, in which the user manifests their own domain to nullify a domain expansion's auto-hit attack, Falling Blossom Emotion shrouds the user in an armor of cursed energy that counter-attacks the moment a domain's guaranteed hit makes contact. The cursed energy defends the user automatically, countering any attack with equal force to nullify it.
Dagon trapped Naobito's team inside his domain and attacked them with an endless stream of shikigami enhanced by the domain's guaranteed hit. Naobito was able to resist the early onslaught of fish shikigami by using Falling Blossom Emotion to cut them apart as they approached him. Even when the number of shikigami was infinitely increased by Dagon's Death Swarm technique, Falling Blossom Emotion was still able to protect Naobito.
However, the pure endless volume of shikigami never slowed down and it blocked Naobito's view, allowing Dagon to get close and punch him. This proved that while Falling Blossom Emotion can resist cursed techniques, it provides little to no defense against physical attacks.