attic; attic space
Refers to the space directly under the roof, especially in a small building or shed; often used in construction and architectural contexts.
I made storage space in the attic.
It is necessary to improve ventilation in the attic space.
Compound of 小屋 (こや, 'small building, shed') and 裏 (うら, 'back, reverse side'), referring to the hidden space behind the roof of a small structure.