Gusco was the leader of a group of pirates that sold children to other countries and the one who hired Apachai Hopachai as a bodyguard.
One day, Gusco threw a piece of food away in disgust, and by pure coincidence it landed by Apachai. Apachai, having been starving at the time, interpreted this as a gesture of good will, and followed Gusco loyally, unaware of his master's true nature. Gusco taught Apachai many immoral things that still somewhat effect Apachai's manner of speaking. For example, whenever he answers the phone, he tells the caller that he has their child hostage and for them to forward the money.
On the day that Hayato Fūrinji and his granddaughter Miu arrived in Thailand, Gusco foresaw a bad omen and said he felt like a demon was watching him, just in time for him to spot Hayato running on the water towards his ship. Soon Hayato ends up fighting Apachai and commends him for "stirring up his spirit". Gusco orders his men to open fire on both of them for destroying his ship and tells his men that he doesn't want his treasure being wrecked. Hayato angrily releases a shockwave at the gunmen for interfering, only to find that Gusco has taken Miu hostage, to which Hayato issues a death threat to him. Gusco tells Apachai to kill the elder. After Apachai explains his reasons for following such a man, he turns his attention to his "master", noticing the terrified children. After finally catching on to Gusco's evil nature, Apachai betrays him and Hayato erases his memories. He is put out to sea in a box and when he wakes up, wonders who he is. His current whereabouts and fate are unknown.