Konami

Konami and Mai are best friends. Konami is a trendy, cheerful and optimistic girl with almost as much energy as Mii and just as much naivety. She rarely thinks of the consequences of her actions.

She is responsible for breaking Mai's cyclical nature of her depression. She becomes a great artist and eventually has a daughter who she decided to name Mai.

Mai, the sister, eventually meets the daughter in the future and at first mistakes her for Konami. When Mai, the sister, returns to be with Konami after meeting with Konami, she asks Konami to teach her daughter that both of them enjoyed their friendship and never resented the other for leaving, hoping to change the personality of Mai.

(Source: Wikipedia)