Are you talking about 鼻濁音 or a pronunciation of ガ行, and not a pronoun? If so, it's not limited to "gi". 鼻濁音 occurs on the particle が and almost all ガ行音 in the middle of words except the number 5(e.g. 105 or hyakugo) in central, eastern and northern Japan.
BTW, if "kyou gishitsu" means 競技室, you shouldn't put a space between "kyou" and "gi". "Kyougi" is one word.