Hello Osamu,
Cool work comrade, very good.
As other great people said, it’s perfect. I’m not very good at design and creativity but I would give some small suggestions.
As you are expert enough comrade, I suggest you get some hand of JS(don’t know if it’s possible with CSS), and give a transparent background colour to top navigation when user starts scrolling to bottom(so it means no transparent when top scroll), also make the top navigation a little smaller(less height).
If you assume the current form when in top scroll, assume following(my suggestion) when it’s not at top), check:
About the project section. For desktop it’s super! but let me note one thing about mobile view.
You know there is no any :hover
thing in mobile. Some mobile browser may simulate the hover when an element comes without any action.
In mobile, user by default see one thumbnail, and he/she might not thinking to click on it for more inline info(just like the hover action for desktop)
So I suggest you place each image(thumbnail of your work) as a captioned box/frame, I think it’s more cool, I did one for you for sampling, please assuming following:

Also I also suggest you apply the same thing for desktop too.
Your project section is awesome, but you know what makes it super awesome? let me tell you one fact.
In very very rare situation, this is possible that an external script gets blocked, or failed to load(let say your jquery plugin) so what happens? there will be no any data about the projects when user click or hover on each one!
Way to be super awesome: One good practice is code the html part in a manner that if all of the scripts get blocked, the page still speak its data. So I refer to my suggestion mentioned above. by default you may let each box come with caption, and when jquery is loaded, you do the extra hover action too.
Another small bug is about the links in top navigation, I’m talking about the “about” and “project” links. If you note, when you click on them(let say “about”) page is scrolled correctly, but “about”(title) is under top navigation border. please check:
You see about is under navigation border, I think it’s not pro.(same thing about the projects)
I suggest you apply a small fix and just scroll it a little less so about/project is placed after navigation border.
I say you will be one mean UI/UX developer, which you already are.
perfect, keep going on great work Osamu, happy programming.