Pyotr is one of Harima's first animals during the series and also one of the most closely related to him. Pyotr has a developed a sense of duty towards Yakumo after Harima's trip. He often called Harima as master, although now he only recognizes him as a friend (maybe because of Harima's change of look).
In the summer days of School Rumble, Harima needed a place to keep the animal friends he had made. He chose the school's gym, as no one would be there during the summer. With Itoko to look after him, this is where Pyotr spent his time. The only people to be nice to him, were Harima, Yakumo, and Sara.
Pyotr is hard to miss, considering, he's a giraffe. And a quite tall one at that. He was tall enough for his head to poke out above tree's of the Yagami Shrine.
Pyotr has lived in various places. Even Pyotr is not sure where he originally came from, but he lived with Harima, and in the school gym. Then up and the Yagami Shrine. He currently lives a the zoo, entertaining children and cheering up Harima when he has a bad day.
Harima was Pyotr's master for a while, after Harima decided to go back to school, he spent less time with his animals, and so that included Pyotr. Soon, Pyotr was sent to the school gym to stay there for summer vacation. After a while, he stopped thinking of Harima as a master, and began thinking of him as a friend.
After Harima sent him to the school, Pyotr had only Itoko to take care of him. Itoko treated him like he was stupid, and was mean. When Yakumo came, she was nice to him and treated him with respect. Pyort really respects Yakumo, and will always remember what she did to help him.
When Pyotr was in the school, Itoko did not treat him fairly, made it hard for him to eat, and kept him cooped up in the school. Pyotr has a kind heart, and does not hate people and make enemies easily, so, this feeling of hatred was very small and brief.