There's a lot to praise here, but the main draw of the show is the progression of the two protagonists' relationship: it feels incredibly natural and is done in a beautiful way. Unlike many other romances, this show doesn't feel the need to oversaturate itself with comedy and us unafraid of being emotionally vulnerable and sincere. The relationship between the the protagonists feels compelling because it is built upon a genuine friendship that is portrayed convincingly. Finally, the depiction of these two gradually deepening their trust and intimacy in one another moved me in a way I didn't expect.
The side-characters weren't standouts, but they also weren't bad by any means, they felt like real people, even if undeveloped (and that's for the best, it's a short runtime and should focus on its primary characters). I would give this show a 9.5/10 for being the most compelling romance narrative I've seen since Steins; Gate.