Question 1

Where is Koyasu Shrine?

Accepted Answer

Koyasu Shrine is in Itabashi, Tokyo, Japan. You can see its exact position from the map coordinates and the Street View link.

Question 2

Which scene of Blue Box does Koyasu Shrine appear in?

Accepted Answer

Koyasu Shrine appears in OP1 of Blue Box.

Question 3

Can I visit Koyasu Shrine?

Accepted Answer

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

Question 4

Where was Blue Box filmed?

Accepted Answer

Anime and manga are not filmed the way live action is. Their backgrounds are painted from photographs of real locations, and Koyasu Shrine is one of those real places (OP1).