Rui

Rui is one of the main antagonists in the Natagumo Mountain Arc of Demon Slayer: Kimetsu no Yaiba.

He is a Lower Rank Five of the Twelve Kizuki (the elite demons serving Muzan Kibutsuji) and the leader of a large spider-like demon family living on Natagumo Mountain.

Key characteristics:

• Physically appears as a young boy (around 12–13 years old) with pale skin, white hair, and red eyes
• Extremely powerful for his rank, with exceptional control over Spider Breathing (a derivative of Water Breathing)
• Uses threads made from his own flesh to create deadly webs, traps, and even puppet-like control over other demons
• Obsessed with the idea of a "perfect family" — he forces demons under his control to act as his "parents" and "siblings," killing and replacing them whenever they disappoint him

Rui is emotionally complex: he desperately craves familial love and belonging, yet his twisted view of family makes him cruel and manipulative. His arc is one of the most emotionally intense early in the series.