Ore ga Suki nano wa Imouto dakedo Imouto ja Nai

Nagami Suzuka is a beautiful third-year middle school student who has excellent grades and is the student council president. She wrote a novel about a little sister who loves her brother too much to cope, and the novel wins a light novel award. After they discuss the matter, Yuu, her big brother, is the one who debuts as a proxy light novel author instead of Suzuka under the pen name Towano Chikai.
Includes volume 7.5 and 8.5.