It feels lacking to me. I think it could've gone for another 3 or 5 chapters to help make things not so rushed. I also find the boy in this to be quite obnoxious. I'd rather have the ending be the MC finally dying and the sister coming back to life. I just feel it'd work better for me. The ending is a bit confusing and I feel like the MC not achieving his goal of dying makes the rest of the story a bit pointless.
Hell, I think it would've been better for the story to be about the MC and the original girl's spirit as they go through time. I even think it'd be better if the story was just a Shoujo Ai/Yuri between the MC in this body and the business chick as there does seem to be some tension there.