looking at the depots on steamdb, there is a depot for the japanese version/language which most likely contains the data_jp.bin and japanese executable of the game which are missing here as that's the only combination that matched the 38.88MB size of the english version/language since both of these depots contain two files
I didn't download this game but in addition to setting the key for the desired language (e.g. - language = Japanese) inside of a text file named "steam_api.ini", "steam_emu.ini", "settings.txt", "settings.ini", "language.txt", "force_language.txt", "RUNE.ini", "TENOKE.ini", "FLT.ini" (The initials for the Scene group "FairLight") or ... etc., some games might also require the additional download of a separate language pack which needs to be found and copied into the installed game's folder in order to enable the use of a certain language other than the default English (For example, see the available, downloadable separate language packs in the "Cyberpunk 2077" game page. You mentioned that there is an "data_en.bin" file. Perhaps there is also a "data_jp.bin" file that is missing.
Attempting to switch out or remove the "data_en.bin" in the hopes of forcing the game to switch to Japanese won't work as this is the cracked, Steam version of the game with English set as the default language that is targeted for the non-Japanese speaking market and not the cracked, original Japanese version of this game with Japanese as the only available language that was | is originally targeted for the native Japanese market).
Also, some of the Scene groups do not list the languages supported by their game releases in their .NFO files. If you look at the .NFO file for this TENOKE release on xRel, you can see that there is no mention of the languages supported. This could be due to either laziness on the part of that Scene group or it may be that their release only supports English (Some cracked releases may only support English or English and a few, but not all, of the languages or all of the languages that the legitimate [retail] version of a given game does). The language support information that I extracted from this game's Steam page applies to the legitimate [retail] version of this game.
In the old days, Scene groups like Razor1911 used to mention the supported languages but the newer Scene groups like TENOKE seem to have neglected to respect those, nowadays, lesser enforced Scene Rulez. Repackers like FitGirl and ElAmigos however, constantly advertise on their official sites (Which are against the rules of this site to link to) the languages supported in their repack releases of the Scene or P2P releases. The Steam language support information may or may not apply to a cracked version of a given game (Unfortunately, I don't have the time to spare to check every single .NFO file for every single game release that is listed on this site just to find out what language(s) is | are supported in each release, especially when the information may or may not be present inside a given .NFO file in the first place. Also, there is no "official" site to go to where all of the language support information for every Scene or P2P release is available. Only the online stores like Steam or GOG display the language support information for a given game).
You can try to email IGG, the administrator of this site and ask him to try to find the Japanese language pack for the TENOKE release of this game, if it exists. His Proton Mail email address is listed on this site's donation page or if you really prefer to play this game in Japanese then you can try to find the cracked, original, untranslated Japanese version on the 'Net using Google.
Thank you for the helpful information. (And even took time to give me a peek of the Behind the "Scenes" on the logistics of the warez, really appreciate it 🙏)
Language settings in tenoke.ini is ignored. (This is a dummy ini, the game runs even without it.)
data.bin and data_en.bin cannot be switched by renaming.
Game doesn't start if you remove data_en.bin
Windows "Region and Language" does not affect the interface.
Tried cmd arguments such as -lang jp, doesn't work.
steamdb does not list any cmd params.
Attempting to switch out or remove the "data_en.bin" in the hopes of forcing the game to switch to Japanese won't work as this is the cracked, Steam version of the game with English set as the default language that is targeted for the non-Japanese speaking market and not the cracked, original Japanese version of this game with Japanese as the only available language that was | is originally targeted for the native Japanese market).
Also, some of the Scene groups do not list the languages supported by their game releases in their .NFO files. If you look at the .NFO file for this TENOKE release on xRel, you can see that there is no mention of the languages supported. This could be due to either laziness on the part of that Scene group or it may be that their release only supports English (Some cracked releases may only support English or English and a few, but not all, of the languages or all of the languages that the legitimate [retail] version of a given game does). The language support information that I extracted from this game's Steam page applies to the legitimate [retail] version of this game.
In the old days, Scene groups like Razor1911 used to mention the supported languages but the newer Scene groups like TENOKE seem to have neglected to respect those, nowadays, lesser enforced Scene Rulez. Repackers like FitGirl and ElAmigos however, constantly advertise on their official sites (Which are against the rules of this site to link to) the languages supported in their repack releases of the Scene or P2P releases. The Steam language support information may or may not apply to a cracked version of a given game (Unfortunately, I don't have the time to spare to check every single .NFO file for every single game release that is listed on this site just to find out what language(s) is | are supported in each release, especially when the information may or may not be present inside a given .NFO file in the first place. Also, there is no "official" site to go to where all of the language support information for every Scene or P2P release is available. Only the online stores like Steam or GOG display the language support information for a given game).
You can try to email IGG, the administrator of this site and ask him to try to find the Japanese language pack for the TENOKE release of this game, if it exists. His Proton Mail email address is listed on this site's donation page or if you really prefer to play this game in Japanese then you can try to find the cracked, original, untranslated Japanese version on the 'Net using Google.