"Could this guy have joined our Lin Yi?"
That's right.
The man was named Chai Po, and the woman was named Ruolan. Both were high-ranking members of the Dark Rising Organization, and key components of its combat forces.
As for when the two infiltrated the Nine Netherworld, that should be asked of Shiva.
In a team of over ten thousand, two unusual individuals slipped in, and he didn't notice.
To say that there are too many people to keep track of seems reasonable.
But he was Shiva, one of the top divine beings, and not noticing this feels somewhat inappropriate.
After following the team into the location of the King of the Nine Netherworld, the two detached from the group, lingering above the palace, watching the King of the Nine Netherworld lead the Ghosts in a battle against the All Celestial Divine Beings.
