is a Japanese light novel series written by Almond and illustrated by Yoshiro Ambe. It was initially serialized on the user-generated novel publishing website Shà Âsetsuka ni Narà  from 2020 to 2023. It was later acquired by Earth Star Entertainment who published four volumes under their Earth Star Luna imprint from June 2021 to June 2023. A manga adaptation illustrated by Yona Età  began serialization on Earth Star Entertainment's Comic Earth Star manga website in April 2022. An anime television series adaptation produced by Magic Bus and Picante Circus is set to premiere in July 2026.
The Duke's has two sisters: Flora, who is beautiful and a candidate to become a saint, and Carolina, who is plain and lacking talent. One day, in order to improve relations with a neighboring country, Carolina is to be married to the second prince, despite rumors that he can be brutal and cruel. After getting married, they realized that Carolina was actually the more talented sister.
Written by Almond, The Oblivious Saint Can't Contain Her Power: Forget My Sister! Turns Out I Was the Real Saint All Along! was initially serialized on the user-generated novel publishing website Shà Âsetsuka ni Narà  from 2020 to 2023. It was later acquired by Earth Star Entertainment who published four volumes with illustrations by Yoshiro Ambe under their Earth Star Luna light novel imprint from June 16, 2021, to June 1, 2023.
During their panel at Anime NYC 2023, J-Novel Club announced that they had licensed the series for English publication.
A manga adaptation illustrated by Yona Età  began serialization on Earth Star Entertainment's Comic Earth Star manga website on April 28, 2022. The manga's chapters have been collected into seven volumes as of October 2025. The manga adaptation is also licensed in English by J-Novel Club.
An anime television series adaptation was announced during the "Earth Star Novel 10th Anniversary Summer Festival" event on July 19, 2025. It will be produced by Magic Bus and Picante Circus and directed by Mitsutaka Noshitani, with series composition handled by Touko Machida, characters designed by Taihei Nagai, and music composed by Supa Love. The series is set to premiere in July 2026 on Tokyo MX, BS11, and AT-X. The opening theme song is "Windmaker", performed by Kaya.
The series won the encouragement award at the 2nd Earth Star Novel Award in 2020.