This article contains spoilers.
The truth of Oni-Kakushi Edit that was revealed in the abolition edition of "The Solution when Higurashi" (Answer Edition).
A part of the hallucinations that Keiichi Maehara who developed the Hinamizawa syndrome saw.
The voice of salvation of Rena, Mion, Satsuko and Rika did not reach him ...
In Onikakushi-hen, after Keiichi had won the Teddy at the Watanagashi festival and gave it to her, it is revealed by Mion that Rena kissed him. Later, Rena quickly notices Keiichi's unusual and erratic behavior and attempts to help and calm him down, begging him to talk to her about his problems and even following him around "protecting him," to ease his paranoia.
She ultimately fails, due to his hallucinations that turn her kindness into treachery, and ends up being killed by Keiichi along with Mion, but only after one final effort to comfort him.
This failure is the subject of her image song, Dear you -Cry-. Keiichi reveals in the monologue at the beginning, which takes place after the murder, that he perhaps loved Rena.