The first step is to make sure the group has clear expectations about the game. Maybe you’re the only one griped by this. Maybe they all are. Often it can be helpful to have a “Session 0” when you start a new game/campaign to talk about expectations. There’s not a “right” tone for a game and you need to realize some of this may be all in your ...
Ask what the group thinks.
In the end, you are not running this game for a single player. That means, you probably are not the only one who might find their actions disruptive. Ask what the rest of the players think and make them confront the problem player. You are not the only person at the table and game ethics are there for everyone to enforce.
When he ...
You should have killed his character
This player believes that nothing they do will have consequences because you'll never be willing to narrate that their character is dead.
I gave him several warnings like "a long forgotten instinct that warns him from a mighty predator" and several NPCs that scream to him that he should run since he is ...
Ask him if he still wants to play
You can't make anyone take things seriously, if they don't want to.
At session Zero he especially said nothing even when i asked him
When you ask "what game do you want to play" and that guy says nothing, perhaps he doesn't want to play at all. It is possible he don't want to quit only because he thinks this will be ...
Be the firm one.
Sounds like you are suffering from several of the well known Geek Social Fallacies.
This guy is disrupting and injuring other people’s leisure despite being asked to stop. This is unacceptable behaviour. The correct social response to unacceptable social behaviour is “There’s the door; put yourself on the other side of it. We’re playing a ...
Having been very close to an L5R LARP's organization group the past half year, I can give a little insight how they promoted not fighting, even as the LARP itself fell into the water due to some events:
There are almost no NPCs!
Almost every character on the LARP was to be a player. Samurai or farmer, it was a fellow player, never an NPC. The few NPCs that ...
Consider running more non-combat storylines.
The LARP takes place during a wedding.
Characters that are in high demand include: Entertainers (musicians, actors, storytellers, jugglers), traders, chefs, visiting dignitaries, craftsmen, family of the bride and groom, local nobility, a priest or two.
Events that will occur include: A feast, a ...