Fate/Outer Code: Type-Andromeda (Nasuverse x OP!Male Reader)

What if the Fourth Holy Grail War had an additional Servant? What if this extra Servant was the single most overpowered jerk summonable? No, not THAT overpowered golden jerk. This one makes him look like a saint with the sheer abundance of his ego.

Forming an unlikely contract with an exasperated, and not too sane, Master, the 8th Servant's arrival causes the events of the Heaven's Feel to radically change. For the better or worse? That remains to be seen.

But he doesn't care about that, he'd rather disobey his Master and annoy everyone as much as physically possible.