One inbox, read by the person who makes the games
0n1 is a one-person studio, so there's no ticket system and no call centre — mail lands with the developer. Player support questions are answered first; everything else as soon as possible.
There is an oni on the door, though — he stands in the corner of every page. He can answer questions about the games straight out of this site's pages, and he'll show you which page he read. He isn't the developer and he can't do anything on your behalf — for that, the email below still goes to a person.