Decidevible is a tall-ish blue devil with black horns, yellow eyes and has a purple tuft of chest hair. He has a particularly round body with very skimpy legs but muscular arms, he wears only black wristbands, a cape that's purple towards the edges and black pants with an angry skull belt buckle and pointed shoes.
Decidevible can cause anyone he possesses to do actions without hesitation.
Yo-kai Watch Animation
In episode 151 Decidevible appeared to Nate and forewarned him in his room that he was going to strike Nate when he least expected it, casing Nate summoned No-Go Kart to thwart whatever he had planned and went out.
While walking Nate runs into Katie who invited him to go ice skating with her and Nate, as usual, got caught in his own fantasy, but Decidevible inspirited him while his guard was down and caused Nate to make a wrong decision but inadvertently got inspirited by No-Go Kart and he starts second guessing his decision, but not for too long and Decidevible pushed No-Go Kart by Katie where she gets inspirited by him and starts sec guessing bringing Nate with her and Decidevible inspirited Nate again, being possessed by him Nate tries to ask her to make her decision but she can't for she is too unsure to.
After which Nate befriended Decidevible and requests him to despose of No-Go Kart and inspirit Katie to have the odds be in his favor.
All goes as planned until Katie's friend Sarah shows up and Katie decides to go ice skating with her and rejectes Nate. Being frustrated Nate attempts to Summon No-Go Kart again but fails due to him not being in a summonable place. Decidevible by the end gave a reserved smile to Nate as if it was what he wanted or purposely sabotaged him.
"Kimetemaō" translates as "Determined demon king".
Decidevible is combination of decide and devil, while also be a corruption of decidable.