Some of Yagami's potential relationship partners are much younger than him (he's 35-ish) but never under 18. There's no actual sexual content in these relationships, and they are fully optional.
There's no sexual abuse of a child, but a central part of the story revolves around school bullying by peers. There are scenes of children bullying one another. One boy attempts suicide due to bullying, but this happens before the story begins, and isn't seen onscreen.
The protagonist also has to fight violent high schoolers at several points, and is able to use strong and sometimes bloody physical attacks on them (although there is an option to make them faint out of fear, rather than be knocked out entirely, once their health is low enough).
There is a depiction of a rotten corpse with bugs on it.
A man has his throat cut - but offscreen; you can hear him gurgling as he dies (the English-language audio is worse for this).
There is a dramatic death about halfway through the story, but the ending itself is not sad, and the credits play over a comedic skit involving the protagonist and his allies.
A frumpy-but-secretly-beautiful female ally of the protagonist is sent undercover at a hostess club. The player is invited to dress her up and do her makeup. Several characters make passes at her.
While walking in the city, the protagonist can be hit by a car if not careful, but there’s no lasting effects at all and he takes almost no damage. He also gets back up immediately and is completely fine.
Partially: a storyline involves someone getting revenge on school bullies, but they were not themselves abused. They press-gang other bullies into doing their bidding.
There is an optional EX attack where you summon a dog and he takes out an enemy, but the dog is not hurt at all. You can easily avoid it by not unlocking the skill or by never carrying dog food.
Nobody is raped, but a woman is groped on a train at one point and footage of the event is shown multiple times throughout. It's central to the main storyline.
The man who is tortured and killed early in the main plot has all of his fingers broken. This is shown in photos and discussed, but not shown with video or audio.
In the main plot, a man who was tortured and killed had all of his fingers broken. They discuss this and show a photo, but there is no video or audio of it.
The main plot involves the suicide of a middle schooler due to bullying. The death of the student isn't shown but they show the bullying that occurs immediately before his death, and it is discussed throughout the game. The bullying can also be difficult to watch.
A footage of a murder is shown, and not only is it quite graphic, you can hear the character’s voice gurgling as they’re being killed. It’s much worse in the English Dub of the game.
No, but the player can go to the Earth Angel gay bar, where the bartender - Mama-san - is a large trans woman with stubble, wearing a dress. She was portrayed sympathetically in the related Yakuza series.