I hand stitch a lot of things, it takes longer than using a machine but works the same. People got by without machines for hundreds of years!
If you’re just learning to sew it’s a good idea to use store-bought patterns for a while. Once you are familiar with them, you will understand better how to make your own because you’ll be able to see the different parts that go into a garment.
There are THOUSANDS of patterns out there, so if you see something you have to have, it’s a good bet you’ll find a similar pattern.
Of course you can always change details like making something longer or shorter, adding straps to a strapless top, or putting on decorations! You can take a mass-produced pattern and make it completely your own just by changing the little things.
i’m mostly interested in Japanese fashion. You think there’d be a similar pattern for those clothes?
You never know until you look! Like I said you might not find something that is exactly the same as what you want, but you can always use a similar pattern and change it a little.
This is one of my favorite websites, it has instructions for making a lot of different crafts including clothes. Try searching it for “Japanese” or “Japan” and you’ll come up with tons of results. Plus if you have a question you can’t find the answer to, you can post it and chances are there is someone who can help you!