Chinese, Japanese and Korean fonts almost always lack italic or oblique faces, because their characters are too complicated to support them well.
I don't know Japanese or Korean, but the lack of italic or oblique faces in Chinese fonts isn't because of the complexity, it's because Chinese doesn't use italics or oblique to indicate emphasis, book titles, etc.
In https://w3c.github.io/typography/#font-style:
I don't know Japanese or Korean, but the lack of italic or oblique faces in Chinese fonts isn't because of the complexity, it's because Chinese doesn't use italics or oblique to indicate emphasis, book titles, etc.
Ref: https://medium.com/@bobtung/best-practice-in-chinese-layout-f933aff1728f