Sagu Aoyama, also known as Sag Aoyama, is a Japanese creator recognized as the original author behind several light novel series that have been adapted into manga and anime. Aoyama was born on July 11, 1981, and is a graduate of the law faculty at Keio University. The decision to become a light novel author came after watching the anime adaptation of The Melancholy of Haruhi Suzumiya in 2006, which inspired Aoyama to pursue writing. After submitting works to various publishers, Aoyama won the 15th Dengeki Novel Prize silver award in 2008 for what would become the debut work, Ro-Kyu-Bu!. The pen name Sagu Aoyama is said to combine the first character of the Japanese syllabary with a desire to eat a curry rich with green vegetables.

Aoyama is best known as the creator of the Ro-Kyu-Bu! franchise. The original light novel series was published by ASCII Media Works under its Dengeki Bunko imprint, with illustrations by the artist collective Tinkle. Fifteen volumes were released from February 2009 to July 2015. The story follows Subaru Hasegawa, a high school student who becomes the coach of a fifth-grade girls' basketball team. The series generated multiple adaptations. A manga adaptation illustrated by Yūki Takami began serialization in Dengeki G's Magazine in October 2010. A separate yonkoma, or four-panel, manga titled Ro-Kyu-Bu! Yonkoma, illustrated by Futaba Miwa, ran from June 2011 to October 2013. An anime television series produced by studios Project No.9 and Studio Blanc aired 12 episodes from July to September 2011. A second anime season, Ro-Kyu-Bu! SS, produced solely by Project No.9, aired 12 episodes from July to September 2013. An original video animation, Ro-Kyu-Bu!: Tomoka no Ichigo Sundae, was released in June 2013.

Following the conclusion of Ro-Kyu-Bu!, Aoyama created Tenshi no 3P!, also known as Angel's 3Piece!. This light novel series, again illustrated by Tinkle, was published in 11 volumes from June 2012 to February 2018. The narrative centers on a reclusive high school student who composes music online and agrees to help three orphaned elementary school girls perform a concert. The series received a 12-episode anime adaptation by Project No.9 that aired from July to September 2017. Multiple manga adaptations were also produced.

Beyond these major works, Aoyama has written other light novel series, including Stage of the ground, Gothic Lolita Ping Pong, and Pocket Ace. Aoyama has also contributed scripts for drama CDs and video games, including titles related to horse racing, which reflects a personal interest in the sport.

A consistent theme across Aoyama's major works is the focus on young girls as central characters, often engaged in specific activities such as sports or music. In public statements, including interviews and afterwords, Aoyama has described these characters as symbols of healing and has acknowledged a deliberate creative focus on their portrayal. Personal hobbies such as playing guitar have directly influenced work, with the musical interests of the author informing the band premise of Tenshi no 3P!.

Sagu Aoyama holds a distinct position in the light novel and anime industries as a creator who launched a successful multimedia franchise with Ro-Kyu-Bu!. The franchise expanded across light novels, multiple manga series, two anime seasons, an OVA, and video games, demonstrating a model of cross-media development common in the industry. Aoyama continued this pattern with Tenshi no 3P!, securing further anime and manga adaptations. The creator's identifiable thematic focus and the commercial success of these adaptations have established Sagu Aoyama as a notable figure within the genre of comedy and sports-oriented light novels featuring young protagonists.