The Crimson Gourd, or Benihisago, is one of the Five Treasured Tools of the Sage of the Six Paths and is practically useless by itself. It needs the combination of both the Seven Star Sword and the Golden Canopy Rope to use it. The Crimson Gourd is able to seal a soul inside it. But it needs certain conditions to be met. First of all, the opponent must have touched the Golden Canopy Rope which draws out a person's word soul. Then the Seven Star Sword cuts the soul from the user and is sucked into the Crimson Gourd. After doing so, the opponent is cursed. A word that they have used most often will be written on the Seven Star Sword. If they say that word, they will be sucked into the gourd permanently. Apparently, if you stay silent for a long period of time, you will also be sucked into the gourd. Since there is no way the gourd can actually know what a word is, it uses sound to track it. This means that saying even any sound that resembles the word will get you sucked into the Gourd. Darui says "and I'll" which sounds similar to his most used word "dull" and he was sucked into the gourd. Before he was completely sucked in, he apologizes to everyone for messing up and changed his most used word to "sorry". This proves that the word recorded is not set and you can still change it.