Wang Yan.
A cultivator of the Heavenly Sword Sect, he was a prodigious talent in his youth, understanding the Immortal Sword Intentions of Breaking the Sky, Changchong, and Immaturity. Upon reaching the Void-refining Realm, he was often assigned by the Nine Sword Elders to confront the Imperial Sect as one of the frontline fighters, showing off his brilliance and belonging to the Heavenly Sword Sect Martial Fighting Fraction.
After reaching the Integration Period, he was granted the title of an elder, but in his haste to make progress, his Sword Heart was unsettled. He sequestered himself in his meditation chamber and did not emerge.
Above is the official explanation from the Heavenly Sword Sect for Wang Yan's disappearance, which is fairly commonplace in the world of cultivation—disappearances often span hundreds of years.
In reality, Wang Yan was confined in the Shuize Shasm, in another form of seclusion.
