It all started when 7 young nobles suddenly woke up to the fact they were utterly dispensable and even undesirable to their powerful noble house - the Cin House.
—
There were four major reasons for noble families in a Boundless Profound World to have a very large number of sons specifically, not just large numbers of children, and some noble families even had a system of secret heirs.
The first was simple elimination by Heavenly Tribulations.
When their children tried to cross into Seven Profound Realms, it was expected to lose as many as a third to the trial of the Heavenly Daos - and truly unlucky families could even lose up to half.
The second reason was natural elimination.
Life was unpredictable, and accidents or other unfortunate circumstances often took the lives of a few heirs even long before reaching the Mortal Transcendence Realm, or perhaps even more unfortunately after being lucky to survive the first elimination by Heavenly Tribulation.
