This kept bothering me so in the end I searched for モリス on Japanese Wikipedia and I now think it must be a reference to Maurice Leblanc, creator of Arsène Lupin, who is, I believe, very popular in Japan. Not sure we actually needed to spoiler that, by the way, but I guess better safe than sorry.
This is why I copy all names I mention from the character list or other people’s posts. If there’s a typo anywhere, it’s possible I have repeated it a dozen times without noticing. 
