Isamu

Isamu is a researcher from Chikyu who put his true passion, monster taxonomy, aside in favor of trying to develop a method of teleportation to pursue his missing friend, Professor Willow. As a tragic consequence, he ended up fused with a rat, but this hasn't stopped his crossplanar search.

Background
Several years ago, Professor Willow vanished from Chikyu. Chikyu is a dangerous place, and most of the people who knew her assumed she was dead. Not Isamu. He was convinced that she was still alive, and as his attempts to search the plane failed, he came to the conclusion that she simply wasn't on the plane. Somehow, she'd found a way to leave this world, and travel to other ones, and if Isamu wanted to get her home, safe and sound, he was going to have to do the same thing.

Isamu toiled for years on a teleportation system that could transport objects at instantaneous speeds across long distances, and succeeded in most ways, but failed to unlock the secrets necessary to travel between worlds. Still, he didn't give up hope, and eventually moved up from objects to living animals. And truthfully, it worked, and worked safely. He could put a pigeon or rat or caterpillar in one teleporter, and in the blink of an eye, a friend halfway across the world could retrieve them from their teleporter.

This was a huge discovery for the sake of healing centers across the region, who could now care for tamed monsters like never before. But this wasn't enough for Isamu. He couldn't afford to risk testing it on humans, but even if it did work for humans, just traveling across the region or world wasn't enough.

Isamu never figured out how to bridge worlds with technology. But on one fateful day, while he was attempting to repair a teleporter station, he did learn that his system worked on humans. Although the system was meant to be disabled, a glitch caused it to transport Isamu to another city, into a teleporter already occupied by a trainer's pet rat.

Isamu staggered out of the teleporter, body twisted and shrunk and covered with fur. The young trainer began to sob, and as Isamu caught a glimpse of himself in the reflective windows of the healing center, his heart shattered.

Ironically, this ignited his spark, and send him scrambling backwards into another world. While his teleporter didn't work, fate clearly still wanted him to find his old friend, even if she might not recognize him anymore.

Capabilities
Since his unfortunate fusion, Isamu has gained the ability to speak with animals, which will be super useful whenever he makes his way back to Chikyu. He's also gained substantially improved reflexes, a sharp set of teeth and claws, and excellent senses. All of this is tempered by the fact that he also got shrunk, and lost an appreciable amount of strength and suave in the process.

Prior to his transformation, Isamu was a skilled researcher, specializing in biology and monster taxonomy. When forced to put his mind to it, however, he also showed an incredible proficiency at more practical-and-physics-based science. He has no notable magic capabilities.