You are
Jimmu,
self-aligned corrupt forum administrator.
...but that's just who you've been pretending to be to blend in.
You are also
Archer (Emperor Jimmu).
Having survived a previous grail war, you have been living alongside society pretending to be a normal Australian citizen. Unlike the rest of the people participating in this grail war who have summoned heroic spirits, you are simply a hero capable of being a master. The catalyst used to summon you in the previous grail war was a fragment of your bow.
Australian: You may post at night.
Heroic Spirit: Because you don't need to worry about protecting a fragile master, you are 1x bulletproof.
Hama Yumi: Once per night, you may kill another player using your sacred bow. You may guess the name of that player’s servant. If you do so correctly, you may gain that servant’s abilities and have their servant become your servant.
Foundation of a new empire (Win Condition): If there are 3 or less players alive at any point and you are one of them, you and those two other players win the game and any player who hasn’t already won the game loses, regardless of their alignment. If both of those players are mafia aligned, their win condition takes priority over yours.