Furuya Jogorou

He is Chihiro's grandfather, who suffers from breaks of dementia. [spoiler]It is later revealed that he used to be professor, who was leading research about zombies alongside Darin. [/spoiler] [spoiler]His case of dementia is revealed to be infact due to the fact that he received multiple times the lethal dosage of the zombie venom during his days as a researcher. [/spoiler]