In the first life, she was a cold and friendly senior sister, and he was a considerate junior brother.
He said he lived for her, but later he actually died to save her.
He would keep these words in his heart for the rest of his life.
The story line begins with the male protagonist having incomplete memories of his previous life, while the female protagonist has no memory and only knows that she has to work hard to practice.
To put it simply, a loyal dog man saves his wife.
Purpose: We all have to work hard to live