To view your progression, get to your statistics menu by hitting your Escape key. On the right side you can see your progression on collectables, you click on View list under the Tokyo Tourism category to see your progression.
To register Tourism sights, you have to select your binoculars in the weapons wheel (or by pressing 1), aim with your right click and click on the location of interest with the left click.
There is a total of 23 Tourism sights to get to unlock this achievement.

From the top of the neon dragon building, look to the right and find two men guarding a small rooftop garden.


You can reach the red building next to the 8 shaped one by jumping on a flying car from the bridge. You can find the DJ glass cabin on one side of the building.


You can reach this building by going through an hidden doorway on the staircase to the right of the building with a huge neon beach facade. The balcony is on one side of the black building.
This is an Akira reference.

This sight can be found on the teal building with the windows popping out. On the second row of windows, toward the back and outside, you can find a couple sitting on the edge.


From the outside of the infiltration mission (with a huge with squared building with primary colored rooms), you can look straight ahead at the 8 shaped building to find someone in their pool.


Straight behind the giant head from the starting area, you can find a round garden with multiple trees and someone meditating.


From the portals tower area, facing the Taxi building is a man stuck in the elevator of that building going up and down.


From the dark grey building facing the neon dragon, look down at a window where a person with a bathrobe is at on a purple background.


From the tp point on the nudist mountain next to the energy station, you can find a naked man halfway through one of the chimneys.


On top of the tall tower next to the mini-golf building, you can find a gorilla climbing it.
This is a King Kong reference.

On one side of the big with building the the brightly colored rooms after the cathedral, you can find a window where a man is dancing among many pills.


From the same building where you can find the elevator guy, you can inside the inside of the giant cat facing the black bridge where you get the bike. Look inside through the window to find a man with multiple cats.


From the entrance of the nudist area, you can find a window on the side of the white building where you can see someone doing a ritual.


From one of the portals, you can arrive at the top of one of the dark buildings, looking towards the portals toward you can see a man on top of the needle of top of the blue building.


Next to the Chimney Sweep sight. Look at the space between the building and the mountain, you can find the Cheshire Cat's tail.
This is a Alice in Wonderland reference.

From the main building in the starting area, face the small nudist garden, look to the left of it, toward the teal and red building, there is a man watching his screen at a window


On top of the neon dragon building (where you complete the Twin Punks mission), you can find a window with two characters.
This is a The Fifth Element reference.

Right next to the Chickaan sight, you can find two people talking around a table behind the white part of the building.


At the entrance of the temple, look at your left, you will find a giant bottle of milk on the facade of one of the buildings. Click on the people under it on the balcony to validate it.


Behind the light turquoise building next to the starting area, you can find a window where there is two people naked: one lying down, the other smoking by the window.


From the top of the hotel, look toward the giant head in the starting area, there is a window with a naked person striking the thinker pose.


From the Omega building, there is a building a building with a banner, on top of it there is someone throwing paper planes.


From the 8 shaped mini-golf building, you can find someone partying by himself with disco lights inside one of the big buildings.

I made this guide to help me complete this achievement since I completely glossed over it during my playthrough. I hope this guide has helped you get this achievement. If it did, a good rating is appreciated.
If you have any suggestion to improve this guide, to correct me on some things, to have better indications or can link me references that I missed, feel free to contact me at any times.