Found this on the japanese thread and I think it's interesting
Fastest singles to reach a million views:
Utakata Saturday night - 12 days
Brand new morning - 12 days
Wagamama ki no mama ai no joke - 13 days
Mukidashi De Mukiatte - 18 days
Sexy cat no Enzetsu -18 days
Are you happy? - 23 days
Ai no Gundam - 26 days
Furari Ginza - 27 days
Jealousy jealousy - 36 days
What is love - 37 days
Fastest singles to reach a 2 million views:
Utakata Saturday night - 29 days
Brand new morning - 87 days
Wagamama ki no mama ai no joke - 29 days
Are you happy? - 101 days
Mukidashi De Mukiatte - 101 days
Sexy cat no Enzetsu - 109 days
What is love - 5 months
Sukatto my heart - 6 months
Ai no Gundam - 6 months
Tiki Bun - 7,5 months