Insomni has pale purple skin with a single red eye accented by pale blue eyeshadow. A single stripe of navy blue goes across her face. She has long white hair worn in two large horns on top of her head, held by navy blue ribbon, and wears a navy blue top with a golden waistband that connects to a gold sash around her shoulders, and her bottom half is entirely navy blue with a golden flame in the end.
Insomni believes that it's more fun if you don't sleep. She also has an obsession for cute things.
When this Yo-kai Inspirits people, she makes them stay up all night, only for them to fall asleep during the day.
Insomni can be freed from the Crank-a-kai. or befriended by beating Insomni's Challenge (finishing Stage 70 in 70 seconds).
Befriended: "If you become my friend, you'll have so much fun, you'll forget to sleep!"
Receiving food (favourite): "Seconds, please!"
Befriended (Yo-kai Watch: Wibble Wobble): "If we became friends I'd be way too excited to sleep!"
Insomni appears in EP021, first in a silhouetted form in Nate's room. Her effect causes Nate to refuse to go to sleep and stay up all night reading comics. The following day, it turns out that Insomni has been Inspiriting everyone at school, giving them severe eyebags and the appearance of zombies. Insomni is eventually identified and threatens to make Nate "sleep forever" for interfering with her. Nate summons Baku to take her on. After their attacks collided, Insomni and Baku have a face off in a wrestling arena in which Insomni is eventually the winner. However, it turns out to be all a dream in Insomni's mind; she had passed out the instant she was hit by Baku's sleeping gas. Slowly rousing awake, Insomni tries to play off her loss but admits that the nap was "refreshing" and surrenders her Yo-Kai Medal. Once she departs, everyone falls asleep as her insomniac effects alleviate. The side effect of Insomni's effects being negated is that nobody is able to fall asleep later that night.
In EP027, Insomni was seen in Yo-kai-lifornia where she is among the Yo-kai waiting in line for the release of the Yo-kai Watch Model Zero.
In EP089, she was summoned by Nate to wake up Slumberhog, who was causing his class to snore away. Insomni refused to do so claiming "Why would you ever wake up someone who's this cute when they're sleeping?!" However, she fell under Slumberhog's effect and went to sleep as well.
In Yo-kai Watch, Insomni operates the elevator to the Yo-kai World.
Similar to Wotchagot, the Japanese name for her Soultimate Move references the title of a Japanese variety show that ran on Kansai TV from 1985 to 1987.