Inui Sadaharu

History

Four years prior to the start of the series, Inui and Renji Yanagi from Rikkaidai were an unstoppable Elementary School Doubles Pairing. Unfortunately, their doubles pairing was ended when Yanagi suddenly moved to the Kanagawa Prefecture.

Inui is a highly intelligent player. He plays what he calls "Data Tennis," which involves collecting and analysing data for a player in order to determine weaknesses. He is even able to determine the exact probability of certain shots being successful. The Data Tennis style actually originated from Yanagi. To his surprise, Data Tennis does not work against Ryoma Echizen who evolves over the course of a match, and Jin Akutsu (although Inui never played against him), due to his natural flexibility making shots unpredictable. Inui also finds it difficult to get accurate data on Shusuke Fuji and Kunimitsu Tezuka. Before Echizen came to Seigaku, Inui was considered the third strongest player of the team, with only Tezuka and Fuji above him.

Inui was beaten by Ryoma, and then lost to Kaoru Kaidoh (who had also been beaten earlier by Echizen and was determined not to lose his spot) at the beginning of the series and became the team's manager. He uses his data to create exercise programs for the team. His most hated innovation would have to be his "Inui Juice" or "Penal Tea" (penalty), a disgusting health drink which is used as punishment. The contents of "Inui Juice" are unknown, but Inui is always coming up with new and "better" recipes. When the team went bowling, Inui's new invention "Aozu" first knocked out Kaidoh and even Fuji (who usually enjoyed drinking the "Inui Juice" or "Penal Tea") as well as the rest of the team. Even Inui himself falls victim to the "Aozu".

Eventually, Inui is able to make it back as a regular by using the data he obtained over the time he was manager, losing to Kunimitsu Tezuka but beating Takeshi Momoshiro. While he's a very good singles player, he usually plays doubles with various partners, most notably his protege Kaoru Kaidoh. His doubling with Kaidoh helped Seigaku overcome their problems with doubles teams (which Ryuzaki considered weak with only the Golden Pair as an effective team).

Techniques

Sonic Serve

A serve used by Inui that is very fast and difficult to return. Inui achieved an even faster version of this serve after removing his weighted wrist band (a part of his continuous training prior to the Kantou tournament) during his match against Hyotei Gakuen's Doubles 1. It is said that this serve has a speed of 197km/h.

Data Tennis

More of a playing strategy than a special move, he collects data during and before the match to defeat his opponent. He uses probability to determine what shot will be made, and where it will go. The effectiveness of his use of Data tennis increased greatly after he implemented a new training regimine (2.25 times more difficult than Kaidoh's, whose own training menu was three times harder than that of the rest of the team, making Inui's training several times as hard as that of the others) in order to improve his ability to physically reach the predicted location of tennis balls.

Although later on in the series, before the nationals, he starts to play a rougher form of tennis that consists of mainly power and speed shots whenever he realizes that his data is useless.

Waterfall

A serve that is faster and stronger than the Scud serve, it set a new record at 212km/h in the nationals. But later the record was broken by the Neo Scud Serve at 215 km/h. Its arc and descent resemble that of a waterfall. It was not named by Inui himself, he had overheard the description of his serve by a kouhai (junior) as resembling a waterfall the engulfs the opponent. It was first seen in the national championship against Hyotei Gakuen in Doubles 2.

Rising Shot

Its is a shot that the user immediately hit the ball after bouncing. Inui used this in his match with Renji Yanagi of Rikkai Daigaku Fuzoku.

Jack Knife

The Jack Knife is a fast, sharp and powerful high-leveled backhand shot made by using the front foot to jump into the air with balance while utilizing a pendulum-like effect of the body to achieve maximum strength. Originally used by teammate Takeshi Momoshiro.