Keeping an Eye on the Mysterious Exchange Student Peruri (謎の転校生ペルーリは見た!, Nazo no tenkōsei Peruri ha mita!), known as The Troublesome Witness in most dubs, is the fifth episode of the 1992 anime series of Calimero.
In this episode, Calimero and friends are curious as to why their new friend Peruri has a bodyguard. Pierrot thinks Peruri is a spy, while Priscilla thinks he's a prince. It turns out that Peruri is a witness who can identify a dangerous criminal. It's up to Calimero and the others to help protect their new friend when the crook's associates come looking for him.