Nothing is known about his childhood,
It is shown that he is married to Wreath and that he is watching her give birth to Koh.
At some time, he is outside and Nico called him and said that that Koh is teasing, Koh attempting to ran away, Guy gave him an advice that a man must take good care of women.
Ever since Guy's death, Koh is eager to go to the top of the Monster Tower to find out the truth if he is still alive or dead.
Because of Guy, Beldo didn't get a chance to get the Ultimate Egg.
Guy's Sword "Sepharim" is stuck to the seal of the Ultimate Egg but now, it's stored on Koh's hands.
After Guy gave an advice to Koh to take good care of women, Koh respected and loved women more than ever.
Without Guy, Koh will never get a chance to get a Red Collar for Kewne to join.
Because of the monsters that Guy stored on his monster hut, Koh's family managed to live on the house by selling all of his monsters, including the Unicorn at the beginning, except for Kewne which is stayed on the top floor based on Beldo's story.