"Boy doll box!" is a free otome game in which you have to solve puzzles and make choices in order to advance through the story. In this game, you will get to know the character of a young man who has a small friend named "Doll" who is inside a tiny box. This game is about the relationship between the two characters and the changes that will occur in their relationship.

The main character is a young man named Takashi Morinozuka, and the main character is the son of the owner of a toy shop. Takashi has a friend named Ken. One day, Takashi receives a box from the owner of the toy shop, and he is told that his friend Ken will be inside the box. The box is so small that Takashi can't see Ken, but Takashi can hear him.