Yo-kai Watch (Japanese: 妖怪ウォッチ, Hepburn: Yōkai Wotchi) is a role-playing video game developed and published by Level-5 for the Nintendo 3DS and the first game in the Yo-kai Watch franchise. Originally released in Japan on July 11, 2013, the game is based on the Yōkai of Japanese folklore, who are said to be ghosts and apparitions that cause mischief in daily life. In Yo-kai Watch, player character Nathan "Nate" Adams or Katie Forester, depending on who the player chooses, is given the titular Yo-kai Watch, which gives him or her the ability to see Yo-kai, after stumbling across and befriending the butler Yo-kai Whisper. Players assume the role of Nate or Katie, as he or she travels around town searching for and befriending peaceful Yo-kai, battling hostile Yo-kai, and solving problems caused by mischievous Yo-kai.

The game was released to a positive commercial and critical reception in Japan, and a steady rise in popularity started a franchise, including a toy line and an anime series, in addition to Yo-kai Watch 2, released the following year for the Nintendo 3DS. Despite the franchise's success in Japan, the game would not be released internationally until 2015, when Nintendo announced plans to localize the game in the West. By November 2014, the game had sold over a million copies in Japan, making it one of the best selling games on the Nintendo 3DS.

While on a bug-collecting school assignment in suburban Springdale, the player visits Mount Wildwood and discovers an unusual capsule machine from which they free Whisper, a ghost-like Yo-kai who gives them the Yo-kai Watch, enabling them to see Yo-kai. The player befriends Cadin and his best friend Buhu before returning home with Whisper, only to find that the Yo-kai Dismeralda has sneaked in while they're gone and has managed to inspirit their parents, causing them to argue about whether they should fix dinner or chores. Dismeralda refuses to leave, so the player summons Cadin to fight her, but she proves to be too strong for him. The player and Whisper befriend 3 more Yo-Kai, head to an intersection and meet Jibanyan, who joins them and the others to fight Dismeralda. She and her husband Happiere reconcile and he inspirits the player's parents, ending their conflict. Dismeralda then befriends the player before she and Happiere leave.

The next day, the player visits their friend, who is upset they unintentionally said mean things to their friend. Upon realizing a Yo-kai is responsible, the player finds and befriends Tattletell, who inspirits their friend and allows them to reconcile with their friend. With the issue resolved, Tattletell reveals that a group of evil Yo-kai had broken several seals, disrupting the link between the human and Yo-kai worlds. The player and Whisper defeat the evil Yo-kai and repair the seals, but not before it frees Slimamander. The two are ultimately saved by a mysterious powerful Yo-kai.

The player and Whisper decide to head to Timers and More, run by Mr. Goodsight, to upgrade their Yo-kai Watch and be able to befriend stronger Yo-kai. In the process, The player befriends Baku, encounters the Oni for the first time, and fights and defeats Sproink.

The next day, after Bear uses his mother's ring as bait to catch the "king of Catfish Pond" and accidentally loses it, his father instructs him to retrieve it. The player and Whisper head to a riverside to find the kappa Yo-kai Walkappa and the ring, only to disturb the Yo-kai SV Snaggerjag. After the battle, Snaggerjag reveals he is the guardian of Catfish Pond and that the group had disturbed the catfish in the area. Afterward, the ring is returned.

The next morning, while on his way to work, the player's father accidentally loses important documents after being inspirited by Wazzat. While retrieving the documents, they befriend Wazzat and receive a bicycle as thanks for saving their father's job. Soon after, they hear rumors about development at Flower Road and encounter the powerful Yo-kai Kyubi, who blackmails them into entering the construction zone at night. In the process, the player and Whisper meet Komasan. They also find that Kyubi had led them to the true culprit: Massiface. After the player defeats Massiface, the rumors stop and Kyubi muses about a greater conflict.

The player visits an art museum with their friend Eddie, who asks them to accompany him in sneaking to the museum at night. After being warped into the museum by Mirapo and evading the museum's security protocols, they battle and defeat Phantasmurai, a suit of armor controlled by a mouse Eddie was trying to observe.