I'm sure many here have a number of Japanese language only LD's and either have some means of viewing subtitles possibly involving old and/or expensive equipment to display the subs directly into the video feed, or you're just completely out of luck. This guide's for the latter.
What you'll need:
0. The LD player + TV + LD (Duh) (Having a remote for the LD Player makes life infinitely easier.)
1. .srt subtitle files for whatever series you have and want to watch
2. A .srt playback program (I'm personally using https://sourceforge.net/projects/penguinsubtitleplayer/)
3. A program to flip the screen (I'm using Minaware's DeskMirror)
4. A PC (A complete toaster of a rig should do fine) that can have two monitors hooked up to it. (Or a laptop & one monitor works too)
5. A spare monitor. (Can be a complete piece of garbage, as long as it works. Possibly a requirement / makes life easier if it's the same resolution as the primary monitor)
6. A piece of transparant acrylic / Plexiglass. (The exact dimensions depend on the size of TV you have.)
7. Some means of attaching said acrylic to the front of the TV.
8. Optional, but helps: Some sort of black sheet to stick behind the plexiglass.
Hardware:
Position the monitor directly in front & below the TV, with the screen somewhere around 45° (This will probably be ajusted later) facing the TV.
Then after the acrylic is cut to whatever size it needs to be, (About just a bit wider than the width of the viewable area of the TV, and about 1.1-1.3 times the height of the desired visable area) attach it in front of the TV angled down, towards the monitor at around 30° from upright. (Again, will probably be ajusted later.) (I used Lego myself, it's abundant and easy to reconfigure.)
Attach the optional black sheet behind the acrylic. (Again, I used Lego here 'cause on top of the other two reasons, it was easy to intergrate into the plexiglass setup.)
Now for Software:
Finding .srt files, depending on the obscurity of the title in question, can either be as easy as hitting the first link that comes up on google, or a multi hour hunt for english soked gold. If all other avenues fail you, the most straight forward way of finding them is to find a rip of the series in MKV with subs (A LD rip for easier timing / bonus points.), extract said subs (Might require conversion into .srt if it isn't already) and promptly delete the possibly multi gig wart of space now occupying your storage space.
The sub player I use is self - enclosed & the screen flipper's install's fairly straight forward & self explanatory, so- (It might make things easier if you make a 100% black photo in .png or something & fullscreen it during playback.) (The Sub Player will almost require some meddling about with, that's up to your personal prefrences.)
For final playback:
Display something on the monitor facing the TV for refrence, sit wherever it is you intend to watch your stuff at & ajust the screen and/or acrylic accordingly (This only works at one distance, and viewing angle can be limited depending on how it's set up.)
Start the screen flipper and .srt player, load corresponding .srt file, then keep the mouse over the play button while it's paused at the beginning.
Load the LD & have TV on, play LD.
As soon as the LD player starts playing whatever it is you're intending to play, hit play on the sub player.
BOOM! Now you have subs with your Japanese LD's!
Here's the setup I'm using:
In practise:
(The exact location of the text can vary wildly depending at the angle it's viewed at.)
If I forgot anything, please let me know.
I hope this helps someone out there, or at least is a interesting case study or something.
