In the game you can play as Nate, Katie, Natsume (Nate and Katie's daughter who earlier appeared in Yo-kai Watch: Shadowside) as well as her friends Touma & Akinori, and Shin (who appeared earlier in Yo-kai Watch: Forever Friends) in three different eras. There are also other characters that can be played as.
Yo-Kai Watch 4 contains various differences from the previous games. It features an improved battle system where humans can fight alongside yo-kai and several new Tribes, amongst other changes.
The game was released for Switch in Japan in June 2019. Later that year, an enhanced version, Yo-kai Watch 4++, was released on both Switch and Playstation 4, which includes the Switch version's DLC.
Yo-Kai Watch 4 provides examples of:
- Actionized Sequel: The gameplay has evolved into a much more action based RPG, akin to Yo-kai Watch Blasters, where even the human fighters can battle too.
- Art Evolution: The game features less stylized, more realistically proportioned character designs for humans.
- Bakeneko and Nekomata: A nekomata, just called "Nekomata", is introduced as Shin's friend from the 1950s.
- The Bus Came Back: After demoted to non-playable in the third game, Katie returns as a fully playable character, albeit not as an alternative to Nate like in the first two games.
- Chekhov's Gun: At the beginning of the game, Nate, Whisper and Jibanyan line up to the Crank-A-Kai to get the new Yokai Watch (though they don't get it) Much later, Katie is guided by Navi Dog to the Crank-A-Kai, and receives the watch from it.
- Costume Evolution: Nate has switched out of his previous red jacket with an orange version of his original shirt underneath it. Now he wears an open red shirt that has a white star on its sleeve, a blue undershirt, and brown sneakers.
- Crossover: GeGeGe no Kitarō characters appear in the game.
- Downloadable Content: A few examples in the Japanese version:
- Downloading the game off the eShop, you will also get a code to unlock Damona.
- Yo-kai Watch 1 for Nintendo Switch will unlock McKracken. This is the first time he has been befriendable.
- A DLC Pack, Yo-kai Watch 4++, adds new areas and Yo-kai, plus a Blasters Mode. These are included by default in the PS4 version.
- Feelies: The Japanese release of the game comes with two Arks that can be used to unlock the item Triple Nyan Claw.
- Old Save Bonus: A code obtainable in the Japanese Yo-kai Watch: Wibble Wobble unlocks Komashura in the game.
- Opposites Attract: Ray O'Light (an energetic sun yo-kai) and Dridzelda (a gloomy rain yo-kai) had a daughter together.
- Raiju: Rai-chan is a young raiju. Their Lightside forms are Rank SS and have the same cutesy toon-design as your average youkai. Their Shadowside form are Rank SSS are much more intimidating.
- Ret-Canon: The game is a sequel to the anime film Yo-kai Watch: Shadowside - The Return of the Oni King. It's mentioned that Natsume and her friends defeated the Oni King prior to the game.
- Serial Escalation:
- Yo-kai Watch 2 introduced time travel. This game expands it by allowing travel to three different eras (1950s, 2010s, and 2040s), plus the Yo-kai World of the past.
- The first two games let you choose Nate or Katie, and Yo-kai Watch 3 had both Nate and Hailey as playable protagonistsnote . This one has both Nate and Katie, plus four other watchers as the main characters.
- Spiritual Successor: With Ni no Kuni II: Revenant Kingdom. Due to switching to a pure Action RPG approach, this game will likely be the closest Ni No Kuni 1 sequel fans will get due to its combat system, given what little of the gameplay has been seen so far.