If you loved Virus, try Crest of Betrayal
A bridge between a film you've already seen and one most people haven't. Crest of Betrayal has roughly 6.0× fewer votes than Virus — it's a deeper cut, not a mainstream recommendation. Here's what they share, and what the second one does that the first one doesn't.
What they share
Both films are directed by Kinji Fukasaku, and they both carry the dread, slow burn mood tags, and they sit in Drama / Horror territory. If that's the register that drew you to Virus, the second film will land in a comparable space — through a different lens.
dreadslow burn
What Crest of Betrayal is
Snowflakes fall on lacquered swords, a lone shamisen plays, in feudal Japan's winter. Shadows of loyalty and deceit entwine. Fukasaku's lens touches dark fantasy.

