Mayu Sakai is a Japanese manga artist known for creating numerous serialized works in the shōjo manga genre, primarily for the monthly magazine Ribon. She was born on January 7, 1982, in Fussa, Tokyo, Japan. Sakai first became interested in drawing as a child and decided to pursue a career as a manga artist after learning the profession existed. She attended the Ribon Manga School and worked as an assistant to Miho Obana, the creator of the series Kodomo no Omocha. Her debut work, Primal Orange, was published in the October 2000 issue of Ribon Original while she was still in her third year of high school.

Sakai's professional career has been closely tied to Shueisha's Ribon magazine, where most of her major works have been serialized. Her early serializations included Boku Tachi no Tabi and Nine Puzzle, but her first notable success came with Nagatachō Strawberry, which helped establish her readership. Following this, she continued to build her reputation with series such as Peter Pan Syndrome and Rockin Heaven. Sakai has cited Rockin Heaven as the most significant artistic milestone in her career, as it marked the first time she consciously focused on creating stories that would excite readers rather than just please herself. She has also stated that her favorite character she has created is Ran from Rockin Heaven.

Among her many works, one of her notable series is Sugar Soldier. The manga was serialized in Ribon from 2011 to 2015 and was compiled into ten tankōbon volumes published by Shueisha. The series, known in Japanese as Sugar Soldier, is a romantic comedy that follows a high school girl struggling with self-esteem issues as she navigates a relationship with a popular classmate. The series has been licensed and published internationally, including in Taiwan by Sharp Point Press under the title Honey Girl作战 and in North America by Viz Media under its original title.

Beyond Sugar Soldier, Sakai has created an extensive body of work. Her other significant long-running series include Rockin Heaven, which ran from 2005 to 2008 and spans eight volumes; Momo, which was serialized from 2008 to 2011 and spans seven volumes; and later works such as Kimi to Dake wa Koi ni Ochinai and Gunjo Reflection. She has also produced numerous short stories and one-shot collections, many of which were published as supplemental material within the volumes of her longer series.

Sakai's artistic identity is characterized by several recurring elements. Her protagonists are often young heroines who experience significant personal struggles, as she has stated a particular fondness for creating unhappy characters. Her artwork features delicate linework, detailed fashion, and the expressive, sparkling eyes typical of shōjo manga. She has noted that she draws inspiration for character designs and clothing from observing trends on the internet rather than fashion magazines, often making the styles appear slightly younger and cuter than real-world equivalents. As of her 2015 interview, she drew the pages of her manga traditionally while using digital tools for color illustrations such as title pages and covers.

Her industry significance is demonstrated by her longevity as a creator for one of Japan's major shōjo magazines and the international reach of her works. In addition to her native Japan, her manga have been published in translation in numerous countries, including Germany, France, Italy, Taiwan, and North America. She has been a guest at international conventions, including appearances at the Manga Comic Convention in Leipzig, Germany, in 2015. While primarily a manga creator, her work has also been adapted into other media, as exemplified by the anime adaptation of Sugar Soldier.