Great Greed (ビタミーナ王国物語, "Bitamina Kingdom Story") is an environmentally-themed RPG for the Nintendo Game Boy released by Namco in 1992.
The game's plot deals with a protagonist whose name you set, but referred to as "Sierra Sam" in the game's promotional materials. Sam, a resident of the "real world," is transported to the fictional world of Greene in order to prevent Biohazard Harry (simply referred to as "Bio-Haz" in the game) from continuing to pollute Greene, a world of seven nations. Sam finds himself stuck in Greene because Microwave, who brought him there in the first place, lost her power in the previous battle. Sam's adventures range from collecting debut records to helping to expose a corrupt politician.
Source: Wikipedia, Great Greed, available under the CC-BY-SA License.