As a fan of huniepop 1, I was upset that my favourite character Miss Yumi wasn't in number 2, until I found out that there are unlockable outfits with references to the first game and I was very happy, here are the ones available. Some characters have unlockable outfits that make them into Huniepop 1 characters. Here I will display which character has the unlockable outfit for each character reference.
In the comments HeeCawRoo rightly pointed out there are HunieCam outfits too, I have listed them now.