Any idea on how to enable +18 content?

How do I play the last 3 characters? They are just black rectangles.

:(

I thought she looked familiar and sure enough she is from the H-game "My Yandere Sister Loves me Too much" I'm willing to bet all the other girls are from H-games as well. So now you can go do you're own "Research"

Do I need to beat the game 3 times to get the easy normal and hard achievements? or if I beat it on hard will it pop all 3 for me?