What makes a film “Japanese” in this age of increasing diversity in the domestic film business, where non-Japanese were once found mostly on the margins?

Anshul Chauhan, who was born in India and came to Japan as an animator in 2011, has been blowing past barriers since he set up his own production company in 2016 with partner Mina Moteki and began directing award-winning films.

His third feature, “December,” marks a shift from his previous two, “Bad Poetry Tokyo” (2018) and “Kontora” (2019), which were uncompromisingly uncommercial. Not that Chauhan is now pandering to the box office, but he has attempted a genre — courtroom drama — more in the mainstream, with a story that delivers taut suspense and well-plotted twists.