The surname of the main human character Nate is Adams.
In the English-language versions of Yo-kai Watch, Nate’s full name is Nathan “Nate” Adams. He is an 11-year-old fifth-grade student whose ordinary life changes after he encounters Whisper while bug hunting in Mount Wildwood.
Nate receives the Yo-kai Watch, a device that lets him see supernatural beings normally invisible to humans. He then befriends Yo-kai, collects their medals, and deals with the trouble they cause around Springdale. His personality is intentionally ordinary: he is cheerful and active, but often frustrated that he is average at many things.
A common source of confusion is the character’s Japanese name, Keita Amano. “Nathan Adams” is the localized English name, while the Japanese version uses Keita Amano. Katie Forester is another central human character, but she is Nate’s classmate and childhood crush, not his surname or alternate last name.