It seems that your self-proclaimed F-rank brother will reign at the top of the school that is evaluated in the game? (Volume 1-9 is the latest issue)

Publisher: KADOKAWA/Media Factory
Author: SORANI, Mikawa Gosuto
Size: 128mm x 182mm
Number of books: 9
Language: Japanese
Category: Youth manga, manga
Latest publication date: 2023-09-22

Synopsis:
Lion King Gakuen, Japan's highest peak school, collects only schools, exercise, family, and elites in all fields. However, the reality is a school with a weak meat -and -strong food where everything is evaluated by the results of the game.
Absolute strong people -It was a world of Shura that only the lion survived. The protagonist, Guren Guren, who wants to live an unbeaten life without a cumbersome life in the back world game, is recognized as the lowest F -rank as expected.
However, he reunited with his sister, Kaikyo Kakuri, who loved his brother sincerely, and the situation changed suddenly. And when the school's "malice" attacks pretty, Guren will show his true ability!