The group of heroes came across a little town, after witnessing how peaceful the people are and how freely/safely the townsfolk seemed to be and after asking around they found out there's another Iop, one who lives up in the mountain behind the town and at the peak in a cave. So being the curious group they always were they traveled through the forest and ascended the mountain standing in front of your cave. They couldn't see anything though from how dark it was inside

"Man!.. This guy needs to invest in some lighting!.." Percival quipped

"Shut up Iop brain! This guy lives in a cave! he probably cant afford it!" Evangelyne retorted

"That may not be the case my dear Cra.. He doesn't want anybody seeing inside. In case we're enemies perhaps.." Ruel Inquired, stroking his beard

"Cool! A secret switch might be in this guys cave!" Yugo's eyes lit up and Az tweeted from Yugo's shoulder

"Well can he come out already?! A warrior shouldn't be making a princess wait!" Amalia chipped in, fantasizing about her own dream warrior"

"Wait.. This feeling... Oh... Woah!! It's him! I can feel it!" Rubilax finally talks without insulting anyone in the group feeling the presence of an elder, much more powerful Shushu and Percival looks at his weapon Rubilax to question him

"HEEEELLLOOOOOO!!! ANYONE THEEEERE!!!" But without warning Yugo shouted into the darkness of the cave

(Obviously this is before Yugo and Amalia got together so somewhere between seasons 1-2 maybe)