new tatami mat; fresh green tatami
Refers to a tatami mat that is newly made and still has a fresh green color, before it fades to yellow with age.
The new house was filled with the scent of fresh tatami mats.
Compound of 青 (ao, 'blue/green') and 畳 (tatami, 'tatami mat'), referring to the fresh green color of a newly made tatami.