Nathan Adams, commonly known as Nate and originally named Keita Amano in Japanese, is the main protagonist of the Yo-kai Watch series across video games, anime, and manga. He is an elementary school-aged boy, typically depicted as an only child with spiky brown hair and black eyes. Nate owns a special device called the Yo-kai Watch, which grants him the ability to see, befriend, and summon invisible spirits known as Yo-kai. This discovery transforms his previously ordinary life into one filled with supernatural encounters.

Nate is characterized by his strong desire not to be seen as average. He dislikes being called ordinary and often goes out of his way to prove himself, sometimes even trying to impress his classmate Katie Forester. He is generally friendly, enjoys spending time with both human friends and Yo-kai, and values companionship. However, his personality can vary depending on the media: in the anime, he is often portrayed as clumsy, irresponsible, and occasionally obsessive, especially regarding Katie, whereas in the games he tends to be more mature and level-headed. He can become easily annoyed by troublesome situations, and his daily life frequently involves embarrassment caused by the mischievous Yo-kai that inspirit him.

Nate's primary motivation is to manage the Yo-kai that affect his world, typically by befriending them or resolving the problems they cause. His role in the story is that of a central hero who uses the Yo-kai Watch to interact with the spirit world, often with the help of his Yo-kai butler Whisper and his cat Yo-kai friend Jibanyan. Over the course of the series, Nate develops from a child seeking excitement into a more responsible individual, eventually marrying Katie and having two children, Natsume and Keisuke, in later storylines such as Yo-kai Watch Shadowside. His notable abilities stem entirely from the Yo-kai Watch, which allows him to see, communicate with, and summon Yo-kai, as well as use special medals to call upon specific Yo-kai allies during conflicts.