Saetomiyu is a Japanese creator known for originating the manga and light novel series All Rounders!!, among other works. The creator self-identifies as a sickly office worker who enjoys writing comedies centered on buddy and friendship dynamics. Saetomiyu is also active as a writer on the user-generated novel platform Shousetsuka ni Narou.

The most prominent work associated with Saetomiyu is All Rounders!!, which is formally titled All Rounders!! Tensei shitara Youjo deshita. Ie ni Izurai node Ossan to Bouken ni Demasu. Saetomiyu is credited as the original creator and story author of the series, which is published by Kadokawa Shoten in its Kadokawa Comics A imprint. The manga has been serialized in Comp Ace magazine since February 2022, with Sei Hirano providing the artwork. The story follows a young girl named Indra who, after regaining memories of a past life, leaves her neglectful family and trains to become absurdly strong before befriending an adventurer named Sword.

Beyond All Rounders!!, Saetomiyu has received recognition through various contests. The work Holy Attribute Magician received a special award at the Kakuyomu Contest. Another title, The Tomboy Princess's Great Adventure, earned a special award at the Dragon Novels Contest, and its light novel has been published with a manga adaptation serialized on platforms including Kadokomi Web and Niconico Manga. Additional ongoing works include Fortress Child Sylvia, which is being prepared for republication by GC Novels, and I, the Villain's Heir. My Sister, the Demon Lord, serialized on Kakuyomu Next. Saetomiyu describes themself as a young girl writer, a playful self-designation that appears in their public profile.