Periplaneta japanna is a subtropical field-dwelling cockroach endemic to southern Japan.

[2] Nymphs and adults are a dark black, and typically live under stones and pieces of wood.

[1] Their ability to bore or live in rotting wood enables their spread via ocean currents.

[1][4] Nymph specimens from Hachijō-jima Island and Naha, Okinawa responded to photoperiodic stimuli quite differently during laboratory-induced diapause tests.

This “might be regarded as the result of divergent evolution” between the parapatric populations.