With his Family dead from a young age, all that remained in Cyril's life was his grandfather.
But even Death claimed his powerful Grandfather, Making the Phantump, the daycare and the key his grandfather gave him all he has left.
Cyril realises that his grandfather and his family aren't normal and that the key to the "Basement" Isnt just a normal key
It's something much better.

-novel is also on royal road , check it out https://www.royalroad.com/fiction/44708/pokmon-god-of-spirits/chapter/711361/the-basement -