Ok, straight up have to ask... would that even be sold in that size/type of container in the first place? I get that it is for the joke here, but... really?

Handles could be that size (1.5L) but even then the one pictured looks slightly bigger than that.

I've seen a few sources on the web stating that you can purchase cheap shochu in 5-liter plastic bottles. I'm not so sure about the quality, though.

5L shōchū bottles on Rakuten