[ 2 syll. ka-ko, kak-o ] The baby girl name Kako is pronounced as K AA-Kow- †. Kako is used predominantly in the Japanese language and it is also derived from Japanese origins. The meaning of the name is summer rainbow.Kako is a variation of the name Keiko (English and Japanese). Kako is unusual as a baby girl name.It is not listed in the top 1000.a-ko, kak-o ] The baby girl name Kako is pronounced as K AA-Kow- †. Kako is used predominantly in the Japanese language and it is also derived from Japanese origins. The meaning of the name is summer rainbow. Kako is a variation of the name Keiko (English and Japanese).