The user converts chakra into timber under the ground and makes it grow rapidly, while forming it into a wooden prison. The size of the prison is based on the user's imagination. From an insect cage to a great prison, one can make it into whatever they want by regulating the amount of chakra used. The timber itself is treated with a chakra coating, making its destruction extremely difficult. During war, it has the great ability to detain prisoners, but it can also be used as a disciplinary measure for quarrelling subordinates.