Latin name help please.

Dear Sir/Madam,

I am interested in writing my name in Latin style.
(I am Japanese for your information)

I am male, so in my understading, the general rule should be to add -
us to the end of my forename and surname.

However, my forename ends with "o" and my surname ends with "a".
I have heard somewhere the names ending with "o" or "a" do not need to
be added "-us", because it has been already seen as Lan-like.

Could you please confirm if this is true, or any other converting rule
can be applied to the case of my name?

Glad if anyone could help!

With best regads,

KO