how to insert japanese text via sql nav or iSQL

[gino jersey]

Hi all. I'm working on a function of an application that sends email where the email body is grabbed from an oracle table.

Now we have a requirement to send the email in japanese.

We tried to insert the japanese text in the oracle table.
When the email was sent it was not showing up correctly.
We only saw question marks.

Our tools to insert the email body in the table are SQL Navigator, iSQL Plus, and SQL Plus.

Can anyone suggest how we can resolve this. What do we need to check? How?

Thank you.