Aubrey O'Day Throws Shade From Japan as Diddy Trial Gets Underway in NYC

Aubrey O'Day is in Japan, but it seems she's got a courthouse in Manhattan on the brain ... because she appears to be throwing some major shade at her old boss at the start of his criminal trial.

The former Danity Kane singer posted a bunch of photos from her trip to Japan on Instagram, but the most interesting thing was the caption -- "Your Honor…"

Aubrey seems to be referencing Diddy's sex trafficking trial in New York City.

As we reported ... Diddy was in court Monday for the start of jury selection. He was wearing a navy sweater over a white collared shirt and told the judge he was feeling some nerves and needed to use the bathroom.

Aubrey's been an outspoken Diddy critic over the years ... applauding Cassie for leveling some serious allegations against him in a lawsuit, and celebrating when Diddy was arrested.

AOD used to be signed to Diddy's Bad Boy record label ... and she's accused Diddy of alleged shady business practices and claimed he made unwanted sexual advances.

Aubrey's been doing the sightseeing thing in Japan ... visiting Osaka, Kyoto, Mt. Fuji and enjoying the famous cherry blossoms -- but it seems Diddy's still got her attention.

Something tells us Aubrey will have more shade to throw once opening arguments begin next week ... and there figures to be some explosive testimony in the trial too.