Well, indeed, this is shit but I'm in anyway
Summary chapter 1.1 and 1.2 ( the only ones so far in English)
A guy dies by a truck (lmao cliche) and a goddess will get reincarnated, the guy discovers that the sister (that died with him) is also reincarnated somewhere in the world too, the boy cry and gets angry, the sister was a yandere and harmed, killed everyone he loved, even friends. The boy gets reincarnated as jack, a genius baby that already discovers magic and tagged as a genius, the parents of jack where lovely with the baby and also a trusted maid was there, one day after the 1st birthday of jack, the maid takes jack for a walk and starts humming for jack to get him into sleep, jack, before falling sleep, remembers that it was the same song the sister singed, and ended with : we finally meet after 15 years nii San . That's it lol