12(Crossover)

An Au where Rimuru became the most powerful god in all universes and travelled between different ones to learn new things and not be bored(of course that he returns to Tensura often, that is the place were his loved ones reside in).

So, when Og Cale was dying, the one to approach him was Rimuru and not God of Death so he got offered a different deal that would allow Cale to go back in time and that Rimuru would help him deal with White Star and any enemies he would have or already had if Cale came to Tensura for him(Rimuru is that one person that sees a traumatized and hurt kid and decides he will be their new guardian xD) which Cale accepts as long as his family would be alive and could live peacefully.

How anything else would go from this is up to the writer but the God of Death could have approached Choi Han and offered him a similar deal to the one he did Og Cale in canon except that he would bring Roksoo, Jungsoo and Soohyuk to the TBOAH world while Choi Han's life span would become smaller(of course that the writer can decide to not have Roksoo in the fic or add him in other way).