*Fingerpokes* Do you have lore for Kappa sun? You lore dumped for Moon but not sun
Okay! Again, so so sorry it took so long to answer this!
So Tayō is very VERY new to the shrinekeeper and Tsukis lives. He shows up in the river within the grounds of their small shrine, trying to trick the shrinekeeper as any other kappa would by seducing the. It might've actually worked if it werent for Tsuki coming back in time to stop him. Just like any other kappa, and many other yokai, his goal was to kill humans.
But he is strange in kappa standards. He didnt like cucumbers or many other kappa customs that gross humans out, he acted strange to others, and kappas dont usually end up that pretty or tall. Why is he like that?
Well its because hes half human. A kappa 'father' and a human 'mother', you can probably imagine how his existence came to be if you know of some of the creepier things some kappas like to do. So he was an outcast among kappas. And its not like he could exactly live among humans either. The reason he ended up back with the kappas again in the first place was because he was thrown out when born, too monstrous for humans to keep.
So its good that mature kappas already live solitary lives, isnt it?