Koko

Koko, also known as Coco, is a yellow female Chocobo who constantly appears as the love interest for Boco.

Final Fantasy V
Koko is Boko's mate in Final Fantasy V. The two Chocobos meet in Pirates' Hideout and have several Chocobo babies together. She is first met by the Warriors of Light at the Chocobo Forest in the Planet R, although Bartz points that she can't be mounted due to her gender.

Chocobo World
In the external minigame for Final Fantasy VIII on the Pocket Station Koko is once again Boco's love interest. Their paths first cross during Boco's quest to find MiniMog. Throughout Boco's journey their paths continue to cross until Koko herself is kidnapped by the Demon King which incites Boco to go and rescue her.

Every time Boco and Koko interact Boco's power increases which results in a more powerful Chocobo summon in Final Fantasy VIII.

Trivia

 * In the Dawn of Souls and 20th Anniversary remakes of the original Final Fantasy, Koko is one of the automatic names the player can choose for the Black Mage job.