I was honestly really surprised by the quality of this video. Your singing voice is really beautiful and full in both your chest voice and head voice, and your technique is quite good. Your vibrato is really beautiful! Shinkai Shoujo is a really difficult song but you pulled it off, so major respect to you.
One criticism that I would give to your singing is that sometimes the rhythms are off. If you record while singing along to something with vocals, that may be the reason - it's hard to tell when you're milliseconds off when someone is singing with you. Otherwise, it may be you haven't practiced the song enough with close attention to the rhythm. I personally am really bad with rhythm, and I find it helpful to just practice with a starting pitch and a metronome - no background music. This method also helps you to be more confident in sticking with the note.
It would also be a good idea to proofread your own singing more. For example, @2:47 on 色 and @3:03 on "あの人" you were off on the pitches quite severely. It may be only one or two notes and it may be only noticeable to a few people, but pitch-perfectionism really shows that you put a lot of work into it. I also hear that you're straining a little on those notes which just means that you have to do some exercises to be comfortable jumping up to that range. If you manage that it'll let you concentrate on other things like getting the pitches just right :)
I assume that you mixed this yourself? I must say, the mixing is really quite good, considering that it's your first upload! However, there are quite a few bits in the latter half where you had to sing louder and it's therefore harder to mix well (THE ETERNAL STRUGGLE) where there's some clipping and the echo from the room is audible. It's likely a consequence of the quality of your mic, so I would suggest investing in a higher quality mic (I'm not well versed in which ones specifically though) or practicing mixing and looking up various tutorials to see what works best for your voice and recording environment and mic.
Some logistical things. You may also want to write a description and title in English to draw in more viewers, since I don't think the Japanese youtaite fandom is very big. If you want to interact with people, I'd recommend making a Twitter account to interact with your fans! You'd be able to post whatever you like - Japanese or English or anything else - and it would be fun for them to have an insight into your thoughts and life. Also, "Original" is written オリジナル to match the "j" sound in "gi". Don't worry, I mess up on this word so much, it's kind of ridiculous.
Overall, very good job and I can't wait to see what covers you come out with in the future!