- Yo-kai Watch: Main game series;
- Yo-kai Watch Busters 2: Befriendable Yo-kai.
- Yo-kai Watch (anime): Major Yo-kai.
Yodelsen appears as an unfoldable figure in a picture story book. He has turquoise skin, grey beard and eyelashes, and eight arms which hold a rod for one of the basic tribes of Yo-kai each.
He also sports a gold headgear with a red jewel emblazoned in the middle and a gold gear with a red jewel as well.
Yodelsen, after being unsealed, sports an impossing demeanor, however he can also be easily startled, as seen when he's captured by Are Bacchino and later when being steadily depowered.
Yodelsen is said to harness the power to turn a human into a Yo-kai. However, his real power allows him to turn Yo-kai into sugar canes. Ironically, he is weak to the Treasure Emblems when those are recollected, as they were used to break the seal on him.
Yodelsen is first fought as a Boss Yo-kai. To do so, the player must first get the Stones to gain access to each of the Treasure Yo-kai Dungeons and befriend each of them. In a similar way to the unsealing of Legendary Yo-kai, the Treasure Emblems are placed around his figure in the book he is unsealed, which gives the player a stone which unlocks the Yodelsen's Labyrinth. Navigate through this dungeon and fight Yodelsen until the Treasure Medal is obtained.
Yodelsen is first mentioned in EP179, in which his unsealing is the main goal of Indiana Jaws as a means to revert his sister Cindy Jaws to a Yo-kai after she is turned into a human. Over the course of the Busters T Arc, Indiana Jaws, along with Jibanyan T, Komasan T, Shovulcan, Nyanses II, and Zomboy, obtain the Medals of the Treasure Yo-kai and their emblems in order to break the seal on him.
In EP206, Yodelsen is finally unsealed, but before Indy demands for him to revert the transformation on Cindy, Are Bacchino appears and abdutcts the Great Treasure Yo-kai with a large spring hand. After Indy and his group finally catch to him and his boss, Gyan Amakano, the latter orders Yodelsen to turn Cindy further into a sugar cane, and Yodelsen further demonstrates his power on an humanified passerby Lord Shrillington, Goofball and Chicken Chukket. Amakano then orders Yodelsen to suck Indy and his group into his world in a book, in which the mafioso Yo-kai begins his assault into the heroes in a variety of forms. However, the tables are turned when Jibanyan finds Meopatra's medal and Emblem, which depowers Yodelsen by bursting his rod of the Charming Tribe. Now knowing the means to win this battle, Indy and his group begin recollecting the Yo-kai Emblems, which eventually depowers Yodelsen completely, and with the combination of their power with the Treasure Gear, they unleash a devastating attack which wipes out Yodelsen and defeats Amakano and Bacchino.
Yo-kai Watch: Wibble Wobble
"Yodelsen" (Japanese: ヨーデルセン Yōderusen) might be derived from "Yo-kai", or perhaps the word "yodel", and the name "Andersen".
- Even if he is not a Legendary Yo-kai, the position of each of the slots for each Treasure Yo-kai reminices of the pages in which Legendary Yo-kai are sealed in the Yo-kai Medallium. The sequence when the Stone for the Yodelsen's Labyrinth is obtained has the Summoning theme for Legendary Yo-kai, which further supports this.