Father's Old Enemy: Ryukotsusei
S1:E53Totosai tells Inuyasha that piercing the heart of Ryukotsusei, the demon that gave his father his mortal wound, will make his Tetsusaiga lighter. Inuyasha then decides to kill Ryukotsusei.
Totosai tells Inuyasha that piercing the heart of Ryukotsusei, the demon that gave his father his mortal wound, will make his Tetsusaiga lighter. Inuyasha then decides to kill Ryukotsusei.