A cat promises a grieving kid he'll help her meet her dead dog at the end of the rainbow, and somehow that works. Jin's plan is ridiculous and small and completely sincere, and it matters more than any grand gesture because it comes from something real. This is five minutes that remember what it feels like to lose something you loved, and refuses to make that small.

Mugi is grieving the loss of a beloved dog named Shiro. Jin, a cat who loves Mugi dearly, promises that the two will meet again. The idea comes from the Rainbow Bridge story that Jin heard from his owner, Kageyama, and Jin decides to bring Mugi to Shiro at the end of the rainbow. To pull it off, he calls on the pigeons and squirrels of the neighborhood, and his big plan gets underway. The one-episode ONA is a gentle story about friendship, loss and the bond between people and their pets.