Who is Signore Addetto from Midnight Magic and what is their importance?

Signore Addetto is the princess's tutor. He is also the first person the princess tells about the ghost's appearance. Signore Addetto, who is loyal to Count Scarazoni, immediately tells him about the ghost. We later learn that Signore Addetto is the one who came up with the scheme of killing the prince and for the count to marry the princess. When Addetto appears to have a change of heart about this scheme, he is killed by Count Scarazoni.