Post above mentions Rola Chen asked Agnes Chan if she could cover her song "Hinageshi no Hana" and not only did Agnes agree, but she helped coach Rola.
There were some great clips on Youtube with Agnes Chan joining LinLin on a guitar/singing duet, but they seem to have been removed.
Anyway Agnes Chan was a teenager in Hong Kong in the 70's who starred in some movies, was brought to Japan to do some singing, and she has been busy ever since.
Not only in the entertainment field, but also in the educational field, and she is a UNICEF Goodwill Ambassador. And still as kawaii as ever.
Here she is when she was just a youngen: