Kidd Gruff, known as Yagi Kenta (八木ケン太 Yagi Kenta?) in Japan, is a young boy from a small town in the Loch Mess area. He met his FM-ian partner, Goat Foo, at Alohaha. When they combine, they become Kung-Foo Kid, a wood-based martial artist known for his exceptional speed.
Neither Kidd Gruff nor Goat Foo appeared in the anime.
Kidd Gruff appears in the Loch Mess village after the events involving Zack Temple and Plesio Surf occur. Speaking to him unlocks his EM Wave Changed form as a secret boss, who can be fought in another area of Loch Mess.
Kidd Gruff is a well-mannered and respecting fighter, and is always ready to challenge Mega Man to a sparring match.
- The word "kid" can mean both a child or a young goat.
- Kidd Gruff's surname is a reference to the Norwegian fairytale Billy Goats Gruff.
- His Japanese surname, Yagi (八木), is also the Japanese word for goat.
- According to the MegaMan Star Force: Official Complete Works, the submission of Kidd Gruff included that Kung-Foo Kid was looking to avenge his parents, who were made into a goat stew.