Grampu has fair skin and pink fingernails. Like Oobi, his eyes are hazel. His eyes are slightly larger than the children's.
Grampu is the grandfather and guardian of Oobi and Uma. He is kind, understanding and teaches the children valuable life lessons whenever he can. Grampu's favorite activities include reading, cooking and listening to music.
- Grampu makes more appearances than both Uma and Kako. The only full-length episode in which he does not appear is "Frieda Friend!"
- In the "Chez Oobi!" episode, Grampu mentions that he has visited St. Louis, Missouri.