Gao Gong didn't recognize the other party before boarding this 'Lolita Host'.
Because the little players brought back all sorts of things from the Cosmic Black Market, including alien pets they bought, black market weapons they acquired, and even alien species' dung they used as toys.
Gao Gong had no interest in checking everything one by one; he merely let the internal inspection systems of the Star Destroyer exclude entities that could threaten it.
Of course, they didn't find the other party.
It's not because the Planet Host has the ability to evade the Star Destroyer's inspection; even if the Planet Host is strong, it is merely Tier 3 architecture, while the Star Destroyer is an entire tier higher.
The real reason the other party managed to slip in was due to the Power of the 'Mechanical Revolution' they controlled.
This Power is bizarre and strong, one of the few existences capable of cross-tier interference with higher levels—as long as it's a mechanical creation.
