A red haired Solver with the title, 'Galileo'. He solves puzzle for money purposes and is often trying to get ahead of Kaito in order to claim the purported treasures offered by the POG. He appears to have a crush on Nonoha and even enters a cross-dressing contest to show her his feminine side. Gammon holds a very competitive rivalry to Kaito. He calls him "Bakaito", a combination of Kaito's name and the Japanese word "baka", meaning idiot. Kaito and him seem to have quite a few similarities, their hot temper being the most obvious.

Gammon is always seen with his leather jacket and pants, giving him a delinquent appearance along with his hairstyle and his way of talking. He also rides a motorcycle.

Upon realizing (after a plot by Rook to separate Kaito from his friends) that Kaito is on another level than him, Gammon does not simply cope with that by distancing himself from Kaito (like Cubic and Ana). After the P.O.G. finds out that he is in fact "Chido Setsu", a mysterious Puzzle Giver from a magazine, Gammon is invited by Himekawa Elena to join them. He eventually passes the test by Bishop and is invited by Rook to join him in the quest of solving the "Puzzle of God". It is then that Gammon makes a radical change in his personality. What used to be a competitive rivalry between him and Kaito turns (seemingly) into pure hatred. Gammon does not want Kaito to solve the "Puzzle of God" as he intends to do it for himself and prove to everyone that he is superior, both as a Solver and Giver. His true motives are yet to be revealed.

After engaging Kaito in a deadly puzzle for the sole purpose of crushing him, Kaito makes a mistake (after seeing the possible future) and is about to kill him, before being called back by Bishop, much to his dismay. It proves his resolve, however Rook and Bishop still remain doubtful of his loyalty towards the P.O.G. (as he is actually a Solver as well) and true motives.

The origin of his name comes from the board game "Backgammon".

(Source: Wikipedia)