Yoshiji Koyama (小山よし治), Waldo in the Vitello and Phuuz dubs, is Misae, Musae and Masae's father and Shin-chan and Himawari's maternal grandfather. He is 63 years old. As a retired teacher, he has much higher standards of public decorum than Hiroshi's father Ginnosuke. This uptight behavior of his sometimes becomes the subject of jokes for Shin-chan and a clash of style between him and Ginnosuke. In one episode, however, he found out that both Shin-chan and Ginnosuke liked him.
Although he is quite stubborn (a trait that passed to his daughters) and conservative, he is actually a caring person. He is also quite childish in some occasions and argues with his wife Hisae Koyama about very minor things, this often results in him and Ginnosuke "fleeing" to the Noharas, causing troubles to Misae. He likes his grandson but gets annoyed because of Shin-chan's attitude. It could be said that the only person he gets along well within the Nohara family is Himawari, whom he is very fond of.
He appeared for the first time in episode 209a.