What is Sunny's real name?

Excuse me, could you possibly clarify something for me? I'm quite intrigued by the mention of Sunny, but I'm wondering if you might be able to enlighten me on the matter of their real name. Is there a specific reason why Sunny chooses to go by this particular name, or is it simply a preference? Perhaps there's a story behind it that you could share? I'd be truly fascinated to learn more.