[Andrenekoi]

Hikki for sure had stronger tie-ins over the years. Ayu last big tie-in was Pray for the Buddha movie that ended flopping. Also, Hikki's sound and voice are WAY more comercial overseas, and this gives her a huge advantage in stream numbers as, unlike Ayu, she still has a small but loyal global fanbase.

It's like when you see a kpop video for an artist that doesn't have much of an international appeal, it has like 10M views, and it's a massive hit in Korea, while idol groups with a stronger global following can easily hit 100M views.