Question 1

Where is Gioia?

Accepted Answer

Gioia is in Nagasaki, Japan. You can see its exact position from the map coordinates and the Street View link.

Question 2

Which scene of Iroduku: The World in Colors does Gioia appear in?

Accepted Answer

Gioia appears in OP of Iroduku: The World in Colors.

Question 3

Can I visit Gioia?

Accepted Answer

Yes. Gioia is a real place you can visit. Check what it looks like on Street View before you go.

Question 4

Where was Iroduku: The World in Colors filmed?

Accepted Answer

Anime and manga are not filmed the way live action is. Their backgrounds are painted from photographs of real locations, and Gioia is one of those real places (OP).