In this story, the protagonist finds himself reincarnated in Japan as a baby. As he grows up, he initially shows little interest in baseball.
During a family outing at a batting center, he suddenly feels the urge to hit a baseball and longs to experience that swing again. Along the way, he meets an interesting boy who will change his life forever.
"Your perseverance is what allows me to stand here today on this diamond field. Now, it's my turn to help you fulfill your dream. I will swing this bat for you because you will always be the ACE in my heart."
This is a good fanfic you should do more fanfic in the ace of diamond universe.
Reveal Spoiler