Ω ni dake wa Naritakunai!!: Isekai Tensei Shitara Ane no BL Manga no Naka deshita

Aspiring manga artist Taisei Kuji is an assistant to his sister, a popular BL mangaka. One day, Taisei was unluckily run over by a truck and found himself reincarnated into the omegaverse world drawn by his sister!
(Source: Fusion Product, translated)