Inui's data tennis allows him to predict the probability of a shot taking place although other factors can disrupt the probability. Though he relies on data, he still trains excessively to keep up with his teammates, taking on a training load 2.25x more than Kaidoh's, which is already 3x ahead of the rest of the team. This allows him to reclaim his spot as a regular by beating Momoshiro. He pairs with Kaidoh in doubles to help Kaidoh train, and Kaidoh's massive amount of stamina is used to let him play alone while Inui gathers data. Though Inui is good at predicting his opponent's movements, he can still be defeated by those who either have never shown him all of their techniques or simply surpass him on the physical level. He also has one of the fastest serves in the series. His Sonic Serve can reach 192 km/h (120 mph), though it would later be replaced by the Waterfall Serve. Its arc and descent resembles that of a waterfall engulfing the opponent, and can reach 212 km/h (~132 mph).