Like Mario, he came to Japan in order to seek money to get out of poverty.
Change was originally from a poor rural village in China. Although he is the second son, he was unemployed due to the single child policy of the Chinese government. He was sent into a life of labor and not treated as human being. He tried desperately to learn Japanese with the Japanese teaching materials that he bought with his small amount of money, aiming to purchase a family register and migrate to Japan to feed his family.
Tobaku Datenroku Kaiji: Kazuya-hen
He is first introduced in the series when he and Mario barge into the room and offer their kidneys in exchange for paying off Mitsuyamas debt. Kazuya, being in the same room and witnessing this, offers them to play in his game, the Salvation game to pay of their debt.
After losing in the Salvation Game, Kaiji picks him and Mario up before he gambles with Kazuya. Like Kazuya when he first met the three, Kaiji also considers them as gems due to the strong bond of friendship they showed during the Salvation game and believes they could help him win the gamble by being there with him.
Tobaku Datenroku Kaiji: One Poker-hen
He and Mario bet their lives on Kaiji in One Poker in order to save him from his first defeat.
By betting their lives lives, they manage to force Kazuya to bet his own life as well towards the end of the gamble.