I Bound Myself to a Destructive Witch - Chapter 395 - 370. Close-fitting

This is a story of a little man who walks forward silently, in awe, and strives to chase his dream.

- Description from novelbuddy

In the year 2057, the world has become a corporate-run utopia for the super-rich, and a hellhole for all the rest. Catherine 'Cat' Leblanc is an orphan that is about as far from super-rich as one can be. When the Incursion alarms start blaring and the sky starts raining hungry xenos, it's just another blemish on an already piss-poor afternoon. A cyberpunk magical-girl alien-invasion LitRPG.It’s exactly as wild as it sounds.

The youngest princess of the country of Stellaus, Marietta, was betrothed in a political marriage to the General of the great militant country, Oltaire. General Belvant was often said to be strong, a fierce and terrifying god of a warrior. On the other hand, Marietta was a delicate flower of a princess. Everyone felt pity for poor Marietta’s situation, however, the truth was that Marietta found the General very dreamy… The story of a 30-year old General with a scary face (who was actually quite nice), and the tiny and adorable 18-year old Princess in their times of conflict and of lovey-doveyness.

He became a teacher at the best magic academy in the empire.
….For being mistaken for someone else.