I look forward to the stereotypical Japanese "zero repercussions" storytelling due to cultural censors, and complete inability to discuss the idea of "casus belli" or "justified self-defense". /s
"Oh, boo hoo, I don't want a war because of me."
Well, sorry to say this Mary Sue, but in some situations it's necessary and unavoidable. And trying to pretend it's not will result in more harm, both to your subjects and others, for both diplomatic and military reasons.
But hey, it's recreational manga in modern Japan, so use of force is automatically evil. I'm sure they'll settle it with tea and sweets, and nothing will happen to the hero, their party, their country, or their families as communal responsibility.
I'm equally against over-the-top revenge stories too -- but it's like there's no middle ground. At least not in these fiction. Closest one I saw was "Okami wa Nemuranai". Where an actual civil war breaks out.