What, You Dare Pretend in Front of Me, the Strongest in the Immortal World? is a Manga/Manhwa/Manhua in (English/Raw) language, Action series, english chapters have been translated and you can read them here.
The world beyond the ancient mirror and the immortal realm within were originally one entity. The true power of this world lies in the hands of the divine beast with the title “Light,” who battles against a formidable enemy, the divine beast with the title “Dark.” In order to prevent the extinction of humanity, the ancestors of Cheng Song sealed off the immortal realm from the human realm using the ancient mirror, with the assistance of the divine beast of Light. Only those with the bloodline of the Yu family can activate the bronze mirror and enter the immortal realm.