Toichi was/is Kaito's father and the first Kaitou KID.
So when Corbeau appeared, I was like: that's totally Toichi. There are, actually, no reasons why Toichi can't be Corbeau.
Why did he show his face if he was just going to say: "I can impersonate anyone, even the one who would shock you the most"? Well, he was either testing Kaito or he wanted to make sure Kaito wouldn't think it was his father. Because, if you remember, Kaito already reconized Corbeau a little when he talked in Toichi's voice.
But this isn't a good reason, because: Why talk in Toichi's voice at all, then? There are two reasons:
- He wanted to test his son's Poker Face.
- He wanted to show that he knew who Kaito was (and that Toichi was his father) so it would be easier to believe that it was Chikage.
Why did he want his son to think it was Chikage? To keep him safe from the people who realized that Toichi was KID and that he's possibly alive and want him dead. If Kaito knew that his father was alive, they might come after him to get to Toichi.
Next up: Then Chikage didn't know.