What's the origin of the Japanese people ?

[Minty]

Observe that eyes of chinese are almost all double eyelids with obscure lines. Also, their facial structure especially around eyes and eyebrows are almost flat.

Most Chinese do not have double eye lids, the examples you picked just so happened to be a group who does.

Many East Asian girls are undergoing eyelid surgery known as blepharoplasty.
The surgery involves making incisions at the top of the upper eyelid, removing the fat, and thus transforming the single 'slanted' eyelid into a double 'creased' eyelid.

Statistics show that 50% of Asian women are born with single eyelids. This surgery is especially prominent in Korea and Japan. Possibly in Chinese societies too but Chinese are poorer (due to communist China) so in general, most can't afford this kind of surgery.

Now looking back japanese eyes, they don't usually have a double eyelid, but the facial surfaces between eyes and eyebrows are not flat, more depth in 3 dimension. Protruding eyebrow and sunken eyes.

It is true a lot of Chinese have flatter features but I do not think most Japanese have 3 dimensional features and I have seen a lot of Japanese and Chinese.

SOUTHERN HAN CHINESE: Eyes are generally placed flat to the facial surface with the double eyelids. Also notice that eye and eyebrows are positioned on almost the same level, giving even flater impressions. The epicanthic fold are heavily expressed. Jaws are wider, and possibly roundly formed

The stereotypical southern Chinese:
•Has almond-shaped eyes
•Is shorter and has a smooth, round face (more than likely, no facial hair)

I think you should not use movie stars as examples because they usually have double eye lids as it is considered to be beautiful in not just Chinese’s taste but in East Asian's perception of beauty in general. Most Chinese do not have double eye lids.

JAPANESE: Eyes are placed deeper inside the skull, giving the sunken eyes with single eyelid, or double eyelids formed along with skull (in chinese face, double eyelids are simply formed with eye folds. Japanese double eyelids, if any, have a clear line aligned with skulls, and expressed outerior on the face surface as opposed to chinese interior eyelid). Epicanthic folds not highly expressed, but idyosyncrasies of eyes are expressed as the narrowly visible area of the eyes. Jaws are narrow, and possible crooked teeth are often observed

Of course Chinese and Japanese don’t really look the same but in comparison to Indians or Vikings...etc they do. It’s just like Germans and French don’t really look the same but in comparison to Koreans or Arabians...etc they do.

My husband is often mistaken to be German in Europe but he is French.
Actually his ethnicity is half Belge half Italian but he is French as he is born and has lived in France all his life.

When I took him to Taiwan for vacation one of the sales girls in the bridal shop actually thought he was Middle Eastern.

So ridiculous just because he has dark brown hair and black beard and her perception of French are either white people who have light brown hairs or blonde hairs. But he has never been mistaken not to be of European descendents from any one else before.