Expecting to Fall into Ruin, I Aim to Become a Blacksmith | Botsuraku Yotei Nanode, Kajishokunin wo Mezasu

The protagonist is reincarnated as a game character from their past life and ends up in a downfall with the antagonist, Kururi Helan. The game does not provide any explanation for why this sub-character is paired with the villainess, but it is not a significant detail.