Since I'm not acquainted with 'the tickle machine fiction story', it's difficult to name the main characters. But it's likely that there are characters who interact directly with the tickle machine. It could be a group of friends who stumble upon the machine and decide to test it out. One of them might be more adventurous and be the first to experience the tickle machine, while the others watch and react. There could also be a character who is more cautious and warns the others about the potential risks of using the machine.
There's no way to know for sure without reading the story, but it could be an inventor character.
I haven't actually read 'the tickle machine fiction story', so I can't tell you the exact plot. But generally, it might be about a machine that has something to do with tickling. Maybe it tickles people in a strange way or there are some adventures related to this tickle machine.
It could be about a machine that is specifically designed to tickle feet in the context of the story. Maybe it's a wacky invention by a mad scientist or part of a strange game.
I'm not sure specifically as there are many works that could fall under 'the machine science fiction'. It could be an inventor who creates the machines, often a brilliant but sometimes flawed character.
As we have no information about the story, the main characters could be various. They might be the inventors of the machine, so they could be smart and creative people. Or it could be the people who are affected by the machine, like workers in a factory where the machine is used.
Since I don't know the specific 'tickle school story', it could be students. Maybe there's a mischievous student who loves to tickle others, or a shy student who is always the target of tickling pranks.
The main character is likely the tickle monster itself.
I don't have enough information to determine the main characters. It could be a scientist who invents or studies the machine, a curious child who stumbles upon it, or a group of adventurers who are on a quest related to the machine.
Since I don't know the details of 'the machine true story', I can't say for sure who the main characters are. But they could be the inventors or designers of the machine. Maybe it's a story about a group of engineers who worked together to build this machine.
Since we don't have the full story of 'the machine real story', the main characters could be diverse. If it's a story about a medical machine, the main characters might be the doctors and technicians who use it to save lives. Or if it's a story about a construction machine, the operators and the managers in charge of the construction project could be the main characters.