Japanese tree frog
This frog looks very similar to Hyla arborea, but it has a spot under each eye.  The adult male frog is 2.6 to 4.5 cm long from nose to rear end and the adult female frog is fromg 2.6 to 4.1 cm long.  But the average size of the adult male frog is 3.1 cm and the average size of the adult female frog is 3.5 cm.  It has disks on its toes for climbing.