Well you know how most smaller town or parts of bigger towns have their own gods and stuff, right? Oyashiro-sama's Hinamizawa's god. Rika's the shrine priestess of the town.

A lot of the villagers, including Rena apparently, believe this illness is a curse from their god and one of the things they get cursed for is for leaving Hinamizawa or something like that.

[...A pause. There's one more bombshell he needs to drop...]