Emergence of the Second Strongest

My master was my everything. She saved me from the depths of the abyss, where I was a sheep waiting to be butchered. One day, she abruptly disappeared from the world. After countless years of deduction and tracing, I found out that all traces lead to her going to the Mountain of Rebirth- -the place, which, in myth's, which led to the Realm Beyond the Sky. The mountain which had never been successfully ascended before. In order to find her, I followed her and climbed up to the peak. The moment I stepped on the summit, I blacked out. -In the next moment, I found myself in a dark place... With my body had regressed to that of an infant's.