Big Windup! (Japanese: おおきく振りかぶって, Hepburn: Ōkiku Furikabutte), often shortened to Oofuri (おお振り), is a Japanese baseball-themed manga series written and illustrated by Asa Higuchi. It has been serialized in Kodansha's seinen manga magazine Monthly Afternoon since September 2003, with its chapters collected in 38 tankōbon volumes as of June 2025.

It was adapted into an anime television series, directed by Tsutomu Mizushima and animated by A-1 Pictures, which aired for 25 episodes on TBS from April to September 2007. A 13-episode second season was broadcast from April to June 2010. In North America, the first season was licensed by Funimation, while the second season was licensed by Right Stuf.

By August 2023, the manga had over 18 million copies in circulation. It won the Tezuka Osamu Cultural Prize for best creative work in 2006 and the Kodansha Manga Award for general manga in 2007. The anime series has been overall well received by critics, praising its story, characters, and emphasis on strategy and teamwork, though its pacing has received somewhat mixed response.

The series, set in Saitama Prefecture, follows the story of Ren Mihashi. Mihashi was the previous ace pitcher in his middle school's baseball team, but it seems that he only got the position because his grandfather was the owner of the school. His teammates (especially the team's catcher, Hatake) hated him, and they always lost their games. Mihashi is thoroughly convinced that he is a lousy baseball pitcher, and feels guilty because he believes that he is responsible for all the losses. Mihashi graduates through middle school with extremely low self-esteem. But in truth Mihashi is really a hardworking and skillful pitcher, and the main reason why his team always lost all the games is because of bad cooperation, because his teammates never talked about the game with him, and they did not try to come up with a plan or strategy to fight against their rivals. Mihashi then transfers to Nishiura High School with plans of quitting baseball because he thinks he is not good enough to succeed at it, though he still loves the game deeply. However, he is dragged into Nishiura's baseball team by their coach, Momoe, while watching the team training outside the field. Assisted by his new teammates (and especially the catcher, Takaya Abe), he grows in stature, confidence and skill, helping his team excel with his own abilities.

Several rival teams feature prominently in the series. Mihoshi Academy, Mihashi's former team where he served as ace pitcher for three years, includes battery partners Kanou and Hatake, along with cleanup hitter Hiroyuki Oda. Musashino First's ace pitcher Haruna motivates his previously indifferent team to improve their performance. The squad includes starting pitcher Naoto Kaguyama, captain Ohkawa, and reserve pitcher Kyouhei Akimaru. Reigning Koshien champions Tosei High School initially underestimates Nishiura, fielding ace pitcher Junta Takase (known for his sinkers and forkballs) and captain Kazuki Kawai.

While growing up in Saitama, Asa Higuchi became familiar with baseball by reading the manga Dokaben. When she was in high school, the story of a local baseball team wound up inspiring her to come up with the idea for her own baseball manga. In the original version, Mihashi never spoke and characters like Momoe, Kanou and Haruna did not exist yet. Following that, she collected data on high school baseball for over 10 years in order to create the manga, and she worked with the school she had attended, Urawanishi High School, in the year prior to the serialization.

Five months prior to the serialization in Monthly Afternoon, Higuchi published a one shot in the magazine titled "The Basic of Basics". The story was centered around the characters of the Musashino Dai Ichi school, who would show up in the series itself.

In May 2024, it was announced that the manga would enter on indefinite hiatus.