The disguise Jiraiya used was the Ninja Art: Toad Hiding Technique.
In truth, it was virtually useless against the "all-seeing" Nagato.
Even the Secret Art: Paper Binding Technique that Ye Chen had replicated could not escape Nagato's detection.
The reason Ye Chen had not stopped Jiraiya from using the Ninja Art: Toad Hiding Technique,
and had even used the Secret Art: Paper Binding Technique himself right under Nagato's "nose,"
was that Nagato's Rain Tiger at Will Technique had limitations.
Nagato could indeed extend his consciousness throughout the Land of Rain and sense unusual disturbances.
However, placing such a heavy burden on his mental power had severe side effects.
Nagato had specially created the Six Paths of Pain to revive Yahiko, and that had already tormented him until he looked neither human nor ghost.
Nagato's real body could not endure prolonged, intensive use of the Rain Tiger at Will Technique.
As such, his consciousness usually only enveloped Amegakure.
Only then could he barely sustain his observation of the entire ninja village without any blind spots.
Especially now, when the Six Paths of Pain had sent most of the Akatsuki's members out to track down the Tailed Beasts.
Nagato dared even less to expend too much mental power, so he could only keep the Rain Tiger at Will Technique's range confined to Amegakure.
Thus, even though the Disguise Technique Ye Chen and Jiraiya used was very "crude," Nagato would not discover them for the time being.
And ordinary ninja could not detect them at all through the ninja arts they used.
So, as long as they stayed away from Amegakure, both of them were absolutely safe.
As for how to remain hidden once they reached Amegakure's outskirts, Ye Chen had his own solution.
By comparison, Jiraiya's Ninja Art: Toad Hiding Technique was