How do you say "This souvenir is from X" where X is a person or a place? Would it be correct to say > []{} to say that 'this souvenir is from Japan'? And if so, can the same form be used to say it's a present from a friend? For example > as in 'this is a souvenir from Yoshi' (given to me by Yoshi)?

The first one you can use (put stress on the and it emphasizes where the souvenir came from). With no stress it's "This is a Japanese souvenir."

For something which literally means that, you can use .

> 'This souvenir is from Japan'
> **** []{}
>
> 'This is a souvenir from Yoshi'
> ****

Bonus: ****