Mauro's master, but the abuse is never directly shown on screen. He sends Mauro to find a book to demoralize him and tell him that he will never be free. The side quest of finding the book is avoidable, however, I do believe that Mauro mentions his master in the main story, so you can’t completely avoid mentions of the situation
A part of the screen shakes when someone loses a Shadowverse battle or if someone takes a large amount of damage, but it is brief (less than three seconds)
All the cards make sounds and some of them could potentially trigger misophonia (hissing, other gross sounds), but I believe there are options to lower the volume and/or turn it off
Some characters (particularly competitive ones like Vivian, Mauro, Zuo, Takuma, and later, Rei) can be violent / show contempt in battle, but with the exception of Takuma, no one does anything agressive outside Shadowverse. (And even then, Takuma is not all that bad, he just takes peoples phones in one of the earlier chapters.)
Mimori has what could be considered an anxiety attack in the fourth part of her side quest after she sees an angry child, but it is relatively minor and she calms down rather quickly
Don’t know if this counts, but Kagura offhandedly mentions that she avoids sleeping to deal with her duties in both the student council and the Shadowverse club
You meet Kagura in the school nursing room, idk if that counts. You can’t avoid this.
Another hospital scene is avoidable if you skip Luca/Lucia's side quest where you meet his sister
I played with Japanese audio, and there is occasional swearing in it (some characters say "shit" in Japanese), but no swearing in the English dub/subtitles
No blatant jokes, but there is a plus sized character who cooks. Jokes around him are mainly just force feeding the player character, nothing about his weight is noted