Nekoma's defensive strategy challenges Karasuno's offense by focusing on their adaptability and consistency. They are known for their "read blocking" technique, where they analyze the opponent's spikers and adjust their blocks accordingly. This makes it difficult for Karasuno to find weaknesses in Nekoma's defense and execute successful attacks. Additionally, Nekoma's defenders work cohesively to cover the court effectively, forcing Karasuno to come up with creative plays to score points.