Akane and Momo's grandfather and self-proclaimed mad scientist. He's one of the developers of the Manifestation Engine, but now he keeps a research lab in Izu Oshima and focuses on his inventions. He pours most of his money into his research, which is one reason why the Isshiki family is poor. He has stated that whilst he does own various patents, he chooses not to profit from them as atonement for the accident that occurred seven years ago.

He is the developer of the Vivid System, which allows Akane and the others to fight against the Alone. However, as the result of an explosion that occurred upon completing the experiment, his mind has been transferred to the body of a stuffed otter named Uso-kun (うそくん), with his human body kept in the fridge for preservation.

(Source: Wikipedia)