Very rarely do I come across professional-grade projects in game jams (of which, I admit, I've only voted in some of and never developed any games for) - but this? I feel like I just played a demo of a professional puzzle VN which got featured on a Steam VN Fest. The writing, as others have also noted, is very natural. Not only that, it actually takes into consideration the language barrier in a realistic fashion.
The audio is expertly sourced and used effectively. Not to mention the original music is incredible in its composition and setting moods.
The story...man, what a well-executed series of twists! I can't really talk about them without spoiling them, but suffice to say I did not expect the ending to give off Deus Ex 1 vibes.
Also, I just have to ask: did you take some visual inspiration from Cryo's early adventure games, namely Dune and Lost Eden? The way the characters are composited into the scenes feels like an evolution of those games' wide shots.
I can't wait for the full game so I can get resolutions to that cliffhanger of an ending.