I've read the novel until the 4th volume more or less so for the ones that want some spoiler here you have:
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To break the curse he has to give to birthday to a child, the first time he gives birth to one and then, after some time he gives birth to two more, and another time he give birth lol he is a child-creator machine and ends up I remember with 8 kids :)
Oh and also, when they are in leonidas he does it with gale (the bear) and he transforms into his animal form and continues to do it in that form jajan't
And Chika becomes something like the expert in medicine in leonidas and makes it progress a lot
Oh amd also the kids grown up, some of them are I think aventurers and others doctors
That's all I remember and I know how to explain
Every time I read a charpter my face turns into that specific pikachu meme, the one with it's mouth open and looking at a fixed point lmao