Question 1

Where is Gakushuin-Shita?

Accepted Answer

Gakushuin-Shita is in Toshima, Tokyo, Japan. You can see its exact position from the map coordinates and the Street View link.

Question 2

Which scene of Saekano: How to Raise a Boring Girlfriend does Gakushuin-Shita appear in?

Accepted Answer

Gakushuin-Shita appears in OP of Saekano: How to Raise a Boring Girlfriend.

Question 3

Can I visit Gakushuin-Shita?

Accepted Answer

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

Question 4

Where was Saekano: How to Raise a Boring Girlfriend filmed?

Accepted Answer

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