Ai Otsuka was very compared to Ayu during her peak, but this may be just because they were both big female soloists. This may be an unpopular opinion, but I do see a strong Ayu influence on some Koda Kumi stuff. Not enough for Koda to be considered an Ayu clone, still... In some sense, I feel like every Avex soloist from the 00's, after Ayu was already Ayu, were styled to at least look a little like her, like Hitomi Shimatani and Alan...
Koda in this one gives me strong Ayu vibes:
If I remember it right, she even had the same composers:
Her, but also very influenced by Namie
Sound-wise, not very much, but visually:
The scenes in the pink outfit almost looks like an Ayu parody: