The introduction / tutorial portion of the game seemed excessively long to me - many scenes convey no substantive information (such as being forced to sign a document you can't read) then moving into a very long linear series of episodes with few meaningful choices and a lot of days that have no content at all besides going outside, 'investigating' a a few of times until the option to sleep becomes available, then repeating.
The actual training scenes are good - very fun - I'd suggest keeping that and the other story rich bits and cutting out anything that doesn't actually advance the introduction. Maybe clarifying the opening scene with Duilio so it conveys this sense of 'oh not another one' a bit more clearly.
I found the reactions of the story characters to the player's arrival varied, interesting and credible - and it is fun to meat them.
My frustration as a player was in the other direction - the PC seems incredibly passive for someone that was sucked into an alternate dimension and is told absolutely nothing about why this happened, if or when he's going to be sent back, and what he's expected to do in the meantime. It just doesn't feel like a plausible reaction to me - why isn't he angry, or sullen, or uncooperative, or looking for someone that will give him a bit more information? There are a huge range of realistic and believable possible reactions by the PC.
It's true you don't want to just dump a bunch of exposition onto the player; however, you do need to provide enough of an introductory framework to give a sense of realism to the PC and provide initial guidance to the player.
I dislike giving unsolicited advice - it's too easy for it to be perceived as aggressive or condescending or similar. If you find what I'm saying useful and I can be of any help to you at all just say the word, I'd be happy to help out. Beyond that, I'm going to keep my nose to myself and stop sticking it into your game uninvited.
-Rick