The characters are surprised to find Lupin talking in his sleep, thinking that, as Mamo in 'The Mystery of Mamo' found out, he didn't dream. Yet he talked in his sleep in the episodes 'Lupin Becomes a Vampire', 'The Name of the Operation is Chuushingura' and 'Keep Your Hands Off the Hot Treasure'. The Part 3 episode 'The Gold Beckons Lupin' begins with him dreaming that he's surfing in Miami. However, dreams mainly happen in REM sleep, and Fujiko's confusion lay in the fact that Lupin was in such a deep sleep he couldn't be woken easily, which isn't usually out of the ordinary, since some episodes portray Lupin as a little bit of a heavy sleeper.