The Heavenly Battle: The Legend of Yao Chen

A prequel to Fights Break Sphere (Battle Through the Heavens, BTTH) detailing the life of Yao Chen. Written and released by the original author of BTTH as an actual physical novel in 2014.
There are no spoilers to the main story, the books depicts Yao Lao growing up, how he acquired his flame and there is a small cameo from Xiao Yan’s mother.