Beyond the boundary of Gehenna, a 10,000-ton red starship approached at moderate constant speed, neither too fast to alarm the locals nor too slow to arouse their doubts. It was a standard, non-hostile, and formal speed used when entering a foreign realm on official businesses.
As such, Thanatos did not attack the foreign red starship when it entered Gehenna's space. Moreover, he quickly recognized it to be a starship affiliated with Nightmare.
"People from Nightmare? How rare of them to visit," Thanatos thought.
As the Realm Lord of Gehenna, Thanatos could easily detect foreign visitors and objects due to his connection with the Gehenna Star.
Generally, only Rank 7 Divine Beings or above could bind themselves to large celestial bodies such as stars. As such, Thanatos's feat was proof of his own talent, regardless of the method used.