Hi,

The character of the my player is a Soshi Shugenja and a acceptetd to acquire the title of the Emerald Magistrate.

Can he purchase kata (rank 1-2) whearas he's a shugenja ? Is it logical in terms of mechanics or narrative games ?

Thanks,

Yes and yes.

They are marked with a diamond because the title grants privileged access, and so anyone can learn them, ignoring any restrictions. Except for clan restrictions! Those can only be overcome if a tech is specifically named.
So much for the mechanics.

Lore-wise, this is a Shugenja who has been granted status of a law enforcement officer and can train as one. That includes martial techniques. It might be unusual and some extra-conservative people might consider it unseemly - but there's nothing outright wrong with it. There are martially trained Shugenja after all, too!

3 hours ago, Myrion said:

There are martially trained Shugenja after all, too!

Tamori, I'm looking at you 😅

Pretty much the whole Kuni family for that matter - they are a shujenga school with default access to kata.

It's no different in reverse from a bushi taking the Stolen Knowledge heritage and having an invocation.

Note that once you've 'spent up' the Emerald Magistrate title, you get voice of authority as a title ability, but the curriculum closes - after this point, no more kata. So be sure to get any you really want!