Nyoijizai, also written as Nyoi Jizai, is a Japanese manga artist and illustrator whose professional career began in the mid-2010s. The creator is best known as the author of Harukana Receive, a beach volleyball manga that was adapted into an anime television series in 2018.

Before becoming a professional manga creator, Nyoijizai studied oil painting as a member of their high school art club. Their initial interest in drawing characters was sparked by a particular video game. The creator's first participation in a doujinshi event was at the Comic Market in December 2010, an experience they initially hesitated to pursue due to a lack of confidence in their artistic skills. For digital illustration, Nyoijizai has reported using software such as Paint Tool SAI along with a Surface Pro tablet.

Nyoijizai made their professional manga debut in 2015 with Harukana Receive, which began serialization in the October issue of Houbunsha's Manga Time Kirara Forward magazine. The series ran for a total of ten tankobon volumes, concluding in 2020. The story follows two cousins in Okinawa who form a beach volleyball team, and the manga was licensed for English release in North America by Seven Seas Entertainment. The success of the series led to a twelve-episode anime adaptation produced by the studio C2C, which aired in Japan from July to September 2018.

Following the conclusion of Harukana Receive, Nyoijizai has continued to create new manga series across different publishers. From 2020 to 2021, they serialized Silver Pole Flowers, a story centered on pole dancing, in Kodansha's Comic Days platform. This was followed by RePAIR: Kono Sekai wa Jizoku Kanou desu ka?, which ran in Kodansha's Monthly Morning two magazine from 2022 to 2023. In 2023, Nyoijizai began serializing Succubus-ka no Majime na Pure-san, also on the Comic Days service. The creator has also contributed short works, including Kanetsuji-san wa Oyogenai for a Young Jump supplement and a contribution to the Lycoris Recoil official comic anthology.

Beyond serialized manga, Nyoijizai has worked on character design and supervision for the mobile game Kirara Fantasia, released in 2017. The creator's body of work frequently features sports and physical activities as central themes, moving from beach volleyball in Harukana Receive to pole dancing in Silver Pole Flowers. Nyoijizai's artistic identity is noted for drawing female characters with soft, welcoming features, and the creator has emphasized the importance of drawing what one likes. Through multiple serializations and a successful anime adaptation, Nyoijizai has established a significant presence within the seinen manga market, particularly in the genre of activity-focused stories with ensemble female casts.