Reimu look at the scene behind the magic mirror. There is a happy Reimu with handsome Marisa as husband and cute little ones. They get tasty food, soft bed and a caring Mister.
What Reimu has is lonelyness. Her peni peni, mamu mamu and forehead is burned so she will never be able to have children. Her food are trash and poo poo. Her bed are hard artificial grass that stab on her feet. Everyday, Mister torture her to the verge of death and then fix her again.
Unfortunately, even in this situation, creature like yukkuri who desired easyness will never be able to think of giving up future and commit suicide.
After the cycle of abyuse and watching the happy family, Reimu finally escape from reality. She starts talking to imaginary children. Reimu believed that what she see is reality, that she's actually living with Marisa and her cute children. The yukkuri that got tortured everyday never existed.
One day, after pulling out Reimu's teeth, Marisa came to save Reimu.
Reimu rejected that, after all, there's never a tortured Reimu anywhere. She doesn't need the sympathy because it made her realize her miserable condition.
Mister then came and showed recording of Reimu watching the family and pretending she's having that happy life. The reality finally breaks Reimu's last mental defence.
Mister then told Marisa he will take away the magic mirror now so they can see each others. At first, Marisa rejected the idea, she and her family don't want to see such an uneasy view. But when threatened about being placed with Reimu and got tortured with her, Marisa gave up about the magic mirror.
Now, Reimu has her eyelid cut and her feet burned. Everyday after torturing, Reimu is forced to watch the happy family. After knowing the reality, Reimu can't pretend anymore, she can only be envious to the family.
In the other side of the wall, the family can't feel happyness again. They now know how lucky they are to be treated as pet. The children can no more innocently exclaimed "Happyness~" because of the guilt from knowing their happyness is from the torture Reimu have. Their yukkuri food now tasted like sand from knowing Reimu only eat poo poo.
Mister enjoyed watching all this.