Kaeru Ryouseirui is an original creator known for authoring the light novel series and the original story for the manga adaptation of The BS Situation of Tougetsu Umidori. The work received the top prize in the 17th MF Bunko J Light Novel Rookie Award. The light novel series began publication in Japan in 2021, with English editions released by Yen Press starting in December 2024. The English version of the first light novel volume was published on December 10, 2024. Subsequent volumes were released in April 2025 and October 2025.

The BS Situation of Tougetsu Umidori follows a protagonist named Tougetsu Umidori, whose life takes a strange turn when a classmate makes an unusual request involving a pencil thief. The story escalates with the arrival of a girl in a cat hoodie who calls herself BS or Bullshit-chan and carries a knife, leading Umidori into a quest to "kill the lies." The narrative blends comedy, mystery, and unexpected plot twists, centering on themes of deception and unusual friendships.

The manga adaptation, which began serialization in the magazine Alive+ on November 27, 2022, features art by Miso Ameiro. The English edition of the first manga volume was released by Yen Press on May 27, 2025. Natsuki Amashiro is credited as the character designer for the project. Kaeru Ryouseirui is credited as the original story author for the manga, while Miso Ameiro handles the artwork. The series is rated for older teen audiences and has been described as a story that keeps readers engaged through a series of bizarre and unpredictable events.