This guide shows how to get to all secret endings in the game: 人形, 農場, and Woods, これを書いている時点では, the 4th level isn’t out yet.
人形
After knocking out the girl (エミリア), pick her up and bring her down to the boiler room.
Then put her in the boiler and she will burn to death.
Go back to the van and a secret cut-scene plays.
農場
After knocking out Karen, pick her up with the wheelbarrow and take her to the graveyard behind the house.
Put her in the open coffin and a beam of light should shine above her.
She will turn into a giant chicken boss and you will have to keep hitting her with your frying pan to defeat her.
Then go back to the van and a secret cut-scene will play
ウッズ
After defeating the witch, pick her up and take her to the revival lake.
Dump her in the water and a beam of light will shine above her.
Go back to the van and a secret cut-scene will play.