|Age||61 years old|
|Hair Color||light brown to grayish white|
|Occupation||Scientist, Former Researcher|
|Anime Debut||Episode 1: "First Operation"|
Kenjirou Isshiki (一色健次郎, Isshiki Kenjirou) is Akane and Momo's grandfather and a genius inventor and scientist. His latest creation was the Vivid System, which acts as a self-defense system against the Alone, which he later gave to his granddaughter Akane.
An accident during the development of the Vivid System caused Kenjirou's consciousness to be displaced into a plush sea otter doll, creating his "other identity" as Uso-kun.
Kenjirou is a bespectacled 61-year-old man with a light brown hair and dark brown eyes, with most of the hair on the top of his head faded to a grayish white. As a scientist who mostly stays inside his laboratory, he has little regard over his appearance, and is often seen wearing a lab coat over a gray shirt and denim shorts, with a simple pair of sandals as his desired footwear.
Despite his age, Kenjirou is a hot-blooded man with an endless supply of energy, although he rarely shows this due to his constant laboratory work. The Isshiki family's rather humble lifestyle can be blamed at him due to his constant purchase of electronic parts and other equipment to push his experiments further, and this fact often annoys Momo, who handles financial affairs in the house.
He shows his love towards the equally energetic Akane through a "click hug", a greeting they usually do when she fetches her grandfather from his scientist work, although Momo appears to dislike seeing them in such a "childish" activity.
Kenjiro was among scientists who involved in Infinite Energy Project which lead to creation of Manifestation Engine. During that time, he and Yuuri Shijo discovered the threat of Alone through the accident seven years prior to the series and tried to warn others only to be decommissioned from the project and labelled as a pariah. Undeterred, he chose to continue the preparation against Alone in a research lab at Izu Oshima. He pours most of his money into his research, which is one reason why the Isshiki family is poor. As atonement from the incident that crippled Mashiro Isshiki and subsequently leading Akane developing fear of heights, he decided not to profit his new inventions.
Birth of the Vivid System
Years after being removed from the Infinite Energy Project, Kenjirou continued working on the Vivid System, and by the present time, is in its final stages. Another routine day for the Isshiki family begins, with Kenjirou joining his two granddaughters for breakfast, and being scolded by Momo for buying more parts for his laboratory, which she blames for their meager lifestyle. Soon, he returns to his laboratory to continue on his work while Akane and Momo go to school.
Later, Kenjirou finally finishes the Vivid System and is just one keystroke away from completing his latest work. Upon pressing that key, an explosion rips through his laboratory. Akane and Momo, who are on their way back home, easily saw the plume of smoke created by the blast, and upon rushing back home, they saw Kenjirou's lifeless body. His two granddaughters were shocked upon realizing that he was no longer breathing, but he soon makes his presence known, although his consciousness is now in the body of a plush sea otter doll, which according to him was probably the effect of the explosion that happened earlier. Afterwards, he decides to hand over the Vivid System Key to Akane.
Kenjirou and his two granddaughters soon hear an emergency alarm, and he quickly deduces that it was the Alone on the attack. After he asks Akane and Momo to move his body to a refrigerator for the meantime, Momo heads to the house's emergency bunker, designed by Kenjirou himself. Meanwhile, Akane and Kenjirou head to Blue Island to check the situation with Aoi, who was supposed to travel there.
With the help of "Wanko", Akane's flying bike which Kenjirou also made, the two travel to Blue Island and attempted to intercept Aoi, who was in the middle of the crossfire between the Blue Island United Defense Force and the Alone that is approaching Blue Island. There, he witnesses Akane activating the Vivid System for the first time, rescuing Aoi from harm.
After the first Alone's destruction, Kenjirou assumed the identity of Uso-kun with his human body preserved until his eventual restoration.
to be added