Yarinaoshi Wanko wa Konse mo Koisuru

Makoto, an office worker who lived happily with her beloved dog, Yota. On March 6, Yota's birthday, she was involved in a traffic accident. But when she wakes up, it's March 6, a year ago. What's more, for some reason Yota is nowhere to be found... but then she sees a handsome man who looks like Yota collapsed in the hallway...!?

(Source: Flower comics, translated)