I prefer to call it "the straightest odachi ever," but yeah it's pretty much a chokuto. It's not a rifle though
Guess I must've misinterpreted the small nub near the base of the hilt-guard and the cutting edge.
well the trigger is used for Dust. The character pulls the nub at the hilt, which reveals a chamber, and places a Dust capsule into the chamber and shoves it back into the hilt. Once the trigger is pulled, the sword now has a "status effect"