Hi,
Apparently Neymar is not Asian but is heritage is quite mixed.
Both his parents come from mixed European and African backgrounds. You can see a picture of a younger Neymar with his family here:
As you can see, none of them look ‘conventionally Asian’.
There’s a common knowledge that he also has Japanese heritage but that is quite common because a lot of Brazilian people come from different backgrounds.
In Brazil, there is one of the biggest Japanese communities outside Japan and the majority of Brazil-Japanese citizens support and root for Neymar! Too bad he is out of the World Cup now due to a fractured vertebrae...
However, there’s still no evidence of him having a Japanese or Asian heritage.