Irus and Tanus were the two planets that Minos and his family intended to visit after Eater, if they failed to find the Divine Tail on that planet. Hearing that the 'King of Beasts' had a history on these other planets helped them solidify their expectations of the worlds indicated by the Sea Serpent.
Pisi's words weren't enough to confirm much, but they were enough to show that the group was on the right track.
'If he had his passages through Irus and Tanus known so far from these worlds, he certainly left an impact behind... Perhaps he lived or built refuges on one of these worlds.' Minos thought to himself, pondering what he would do in the Beast King's place.
