... I'm afraid that my review might come off as a bit too harsh. Since this is your first game, I'll try to tone down the criticism.
*ahem* Let me start out with the art. It wasn't bad (definitely better than what I could do, that's for sure), but you could have spent more time polishing up the character sprites. The backgrounds were okay as well, but it could be better. I suggest that you try to soften the edges around each object instead of using really bold outlines.
The music you used was fine. It fit the mood of the situation when appropriate.
Now here's the part where I turn into a nasty little demon

When playing VNs, I rely on the dialogue to tell me the story. When the dialogue is terrible, then the story suffers. If the story suffers, then the whole VN is ruined. Good art or not, people won't like a VN without a decent plot. That in mind, your dialogue was really bad. When you said "several Japanese words (in romaji) may be used," I was thinking, "I'm okay with that. A couple words here or there won't be too distracting." So I powered on the game without downloading the Word document. That was a terrible mistake on my part. One minute into the game and I already had a headache from reading the text.
My rule of thumb for using foreign words in a mainly English work: use phrases whose meanings are commonly understood. Examples would be 'adios' meaning 'goodbye' in Spanish, 'níhǎo' which is Chinese for 'hello,' and 'guten morgen' meaning 'good morning' in German. They're short and simple, and most of the time you can infer their meaning in context if you don't know them. However, a lot of people may not know that 'Ano hito wa dare desu ka?' is Japanese for 'Who is that person?' I sure as hell didn't know because I don't study Japanese. I had to constantly check back to the Word doc to see the meaning of some phrase I couldn't read, and that annoyed me to no end. Besides that, often times you would put the English translation first and then the original Japanese phrase after it or vice versa. That's redundant and silly since the character is basically repeating himself over and over again. "Kanojo desu ka? Is that your girlfriend?" That basically means, "Is that your girlfriend? Is that your girlfriend?" I GET THE POINT ALREADY

NO SHE IS NOT MY GIRLFRIEND, SHE'S JUST SOME RANDOM GIRL I MET AT THE RESTAURANT I WORK AT.
I was annoyed the whole time since the entire game was like that, so I was thankful that the game was short. "Oh no! Ikenai!" "You're so kawaii when you sleep. But that's why you're a bishonen." "I'm a kuishinbo, a self-proclaimed glutton." Seriously, that's weeaboo (or Japanophile) speak. I have a strong dislike for weeaboos, and there were weeaboo vibes everywhere thanks to the mangled up Japanese-English dialogue EVERYWHERE. Honestly, chose one language or the other. If I spoke half in Chinese and half in English, people would quickly get annoyed. "Níhǎo! Wǒ think you hěn kě'ài, so can wǒ have a hug?" That was terrible, wasn't it? That was basically how all of your dialogue was.
But enough ranting from me. Please stick to English and use Japanese words
sparingly. Next time you should get a proofreader to catch the numerous grammatical mistakes you make, and try to extend the story to be longer than 5 minutes of gameplay. There's lots of room for improvement, so don't let my complaints stop you from making VNs. Just remember that you're making an
Original English Language Visual Novel, so stick to what you know best and do not force yourself to emulate Japanese culture.
BTW, I can't comment on story because there was hardly any. The boys were meh at best.