This looks like some Justicia sp.  (ID please).
Family: Acanthaceae
Date/Time: 10th Nov. 2008/ 03:30PM
Location: Mizoram
Habitat: Wild
Plant height: Approx. 80 cm
Leaves: Opposite, Lance shaped, base tapering, 8 to 9cm

I agree that this is a Justicia species but I am afraid, I don’t know them well enough to name it. I guess when the covid pandemic is over, I could bring together images of all the unidentified Justicia species from NE India and try to identify them all.

May I request you to pl. post keys of Justicia from Mizoram.

Could not find a match with the listed species in flora of Mizoram.