Tengloom, much like his name implies, resembles a Kurama Tengu crow-like creature with blue feathers, and a black beak. He wears a khaki shirt with a brown-orange vest over it, brown pants,a tokin cap, and geta sandals. He's always seen carrying a textbook with a purple cover.
Tengloom has a very pessimistic disposition that he passes on his targets. When Nate first summoned him, he says, "Whatever. You think i can't do it anyway.", showing a strong feeling of defeatism.
Tengloom can make his targets assume a gloomy personality by swinging his leaf fan. Unless someone makes Tengloom smile, the effects will wear off.
Yo-kai Watch animation series
Tengloom first appears in EP024, in which he causes Katie, Bear, and Eddie to be gloomy in a search of flowers. When confronted by Nate, Tengloom simply states that he is a minor Yo-kai and nobody knows him. Nate tries to stop him by sending Jibanyan, but Tengloom quickly inspirits him and causes the cat Yo-kai to become gloomy. He also causes Whisper to feel down over himself when Nate asks him for help. Nate summons the Yo-kai dancers to make Tengloom grin, but to no avail. Finally, Nate and his Yo-kai friends use a portable shrine to carry Tengloom over there, but it does not seem to work until they fall over the stairs, which surprisingly causes Tengloom to grin and give Nate his Yo-kai Medal.
Later, he accompanies Nate, Whisper and Jibanyan when Whisper talks about his supposed friendship with Tengu.
In EP026, Nate summons Tengloom as a try to stop Peckpocket. The tengu Yo-kai feels down and tells Nate that he cannot do so anyway. Peckpocket robs him of his book, but he takes another, and it repeats until he is robbed of his clothes as well.
Tengloom appears on trees around Tranquility Apts. at night (Shopper's Row), as well as the 2nd and 3rd floors of the Construction Site at night (Downtown Springdale).
Tengloom also appears on the 3rd and 4th Circles of Infinite Inferno.