Pochimi

Pochimi was a dog that appeared at the start of Episode 1/ Chapter 01. It was almost run over by a car when he dashed across a road, but was saved by Saiki Kusuo. It was later revealed that a parallel world exists in which Kusuo did not save Pochimi and felt a huge regret after seeing it die, hence from then on resolving to use his powers to aid others, and became a very well liked character.