While this achievement is not complicated at all, it can be kind of tricky and take some time. You may even need to do it a second or third time, not sure if this is a bug, hope you can get it the first time.

I do not recommend browsing this guide until you have finished watching all the endings due to SPOILERS contained in the images and the dialogue lines themselves.

• You need first to collect 5 images for each character, unlocked from their respective routes, those contain a rose stamp in the preview found at the gallery.
  
• Each image has 5 different dialogue lines, you'll need to control+left-click around the image in order to find them.
  
• Some of the images have a second one inside with a different set of dialogue lines, press Z in order to show them. I've marked those as a and b.
  
• In general there are 3 locations in each image, one of them has up to 3 lines.
  
• Once you have found the 175 lines the achievement will should unlock.
  
• One of the images needs to be scrolled down with the arrow keys to find its last line, I've indicated it above said image.

*Updated May/27/2019

1.



2.



3a.



3b.



4.



5a.



5b.

1a.



1b.



2. (Use the down arrow to scroll the image for the last line)



3.



4a.



4b.



5.

1.



2a.



2b.



3.



4.



5a.



5b.

1.



2a.



2b.



3.



4a.



4b.



5.

1.



2a.



2b.



3.



4.



5a.



5b.