Rika Furude is the true main protagonist from Higurashi: When They Cry and the main protagonist of it's sequels Gou and Sotsu. She is the daughter of the shinto priest in Hinamizawa. She is the miko, or shrine maiden, of the Furude Shrine, appearing in miko garb for her part of the Watanagashi Festival.

Who killed Rika at the shrine?

Shion confronts Rika about the murders at school, leading to a confrontation between the two. Rika invites herself to the Sonozaki estate where Rika commits suicide by stabbing herself repeatedly in the head, after Shion injects the syringe on her. Shion then invites Satoko to capture her.

Is Rika and Bernkastel the same person?

The name Frederica Bernkastel comes from the name Rika originally used in Saikoroshi-hen FURUDERIKA-Bernkastel; eventually this became "Frederica Bernkastel."