Darn you chuuni lord.

Again with the use of forbidden characters in pool titles; in this case '/'
Kantai Collection - Kancolle/Grand Order (tsukemon)

Not everyone uses Fisher-Price OSes.

.
Michigan Tech: Characters to Avoid in Directories and Filenames

Therefore, it is essential to play it safe and avoid common illegal directory and filename characters.

Makes me wonder how old is that document, I would say 1997.

Wouldn't matter, because they're still illegal. Saving conventions don't change.

To be exact most of this applies to poor old Windows:

https://support.microsoft.com/en-us/help/905231/information-about-the-characters-that-you-cannot-use-in-site-names--fo

The only illegal characters in Linux and Apple ( both being Unix-like ) are / and \0 --- although it's still best to avoid the others MS lists out of respect for Windows users. And to make pretty urls.

[ \0 is called null ] And of course Windows can have restrictions on the length of a filename.

Then it's a problem with our "Fisher-Price OSes", not yours. In any case, if you can't tell the difference between an archive filename and a pool title I'm afraid the mods can't do too much for you.

If you feel like using bloody long filenames for everything, I suggest you to change the invalid characters by yourself on your own unpopular OS.

For the record:
Filename: __akashi_and_akashi_azur_lane_fate_stay_night_fate_series_and_kantai_collection_drawn_by_tsukemon__0f67976e3d686906d8064e57970b661b.png

Pool title: Kantai Collection - Kancolle/Grand Order (tsukemon)

While the character may a breach of conventions in certain situations, this is not one of those situations.